swarm: client-side MRU signatures ; BMT fixes ; network simulation tests

Our original wrapper code had two parts. One taken from a third
party repository (who took it from upstream Go) licensed under
BSD-3. The second written by Jeff, Felix and Gustav, licensed
under LGPL. This made this package problematic to use from the
outside.

With the agreement of the original copyright holders, this commit
changes the license of the LGPL portions of the code to BSD-3:

---
I agree changing from LGPL to a BSD style license.

Jeff
---
Hey guys,

My preference would be to relicense to GNUBL, but I'm also OK with BSD.

Cheers,
Gustav
---
Felix Lange (fjl):
I would approve anything that makes our licensing less complicated
---

* swarm/storage/mru: Add embedded publickey and remove ENS dep

This commit breaks swarm, swarm/api...
but tests in swarm/storage/mru pass

* swarm: Refactor swarm, swarm/api to mru changes, make tests pass

* swarm/storage/mru: Remove self from recv, remove test ens vldtr

* swarm/storage/mru: Remove redundant test, expose ResourceHash mthd

* swarm/storage/mru: Make HeaderGetter mandatory + godoc fixes

* swarm/storage: Remove validator prefix for metadata chunk

* swarm/storage/mru: Use Address instead of PublicKey

* swarm/storage/mru: Change index from name to metadata chunk addr

* swarm/storage/mru: Refactor swarm/api/... to MRU index changes

* swarm/storage/mru: Refactor cleanup

* swarm/storage/mru: Rebase cleanup

* swarm: Use constructor for GenericSigner MRU in swarm.go

* swarm/storage: Change to BMTHash for MRU hashing

* swarm/storage: Reduce loglevel on chunk validator logs

* swarm/storage/mru: Delint

* swarm: MRU Rebase cleanup

* swarm/storage/mru: client-side mru signatures

Rebase to PR #668 and fix all conflicts

* swarm/storage/mru:  refactor and documentation

* swarm/resource/mru: error-checking  tests for parseUpdate/newUpdateChunk

* swarm/storage/mru: Added resourcemetadata tests

* swarm/storage/mru: Added tests  for UpdateRequest

* swarm/storage/mru: more test coverage for UpdateRequest and comments

* swarm/storage/mru: Avoid fake chunks in parseUpdate()

* swarm/storage/mru: Documented resource.go extensively

moved some functions where they make most sense

* swarm/storage/mru: increase test coverage for UpdateRequest and

variable name changes throughout to increase consistency

* swarm/storage/mru: moved default timestamp to NewCreateRequest-

* swarm/storage/mru: lookup refactor

* swarm/storage/mru: added comments and renamed raw flag to rawmru

* swarm/storage/mru: fix receiver typo

* swarm/storage/mru: refactored update chunk new/create

* swarm/storage/mru:  refactored signature digest to avoid malleability

* swarm/storage/mru: optimize update data serialization

* swarm/storage/mru: refactor and cleanup

* swarm/storage/mru: add timestamp struct and serialization

* swarm/storage/mru: fix lint error and mark some old code for deletion

* swarm/storage/mru: remove unnecessary variable

* swarm/storage/mru: Added more comments throughout

* swarm/storage/mru: Refactored metadata chunk layout + extensive error...

* swarm/storage/mru: refactor cli parser
Changed resource info output to JSON

* swarm/storage/mru: refactor serialization for extensibility

refactored error messages to NewErrorf

* swarm/storage/mru: Moved Signature to resource_sign.
Check Sign errors in server tests

* swarm/storage/mru: Remove isSafeName() checks

* swarm/storage/mru: scrubbed off all references to "block" for time

* swarm/storage/mru: removed superfluous isSynced() call.

* swarm/storage/mru: remove isMultihash() and ToSafeName functions

* swarm/storage/mru: various fixes and comments

* swarm/storage/mru: decoupled cli for independent create/update
* Made resource name optional
* Removed unused LookupPrevious

* swarm/storage/mru: Decoupled resource create / update & refactor

* swarm/storage/mru: Fixed some comments as per issues raised in PR #743

* swarm/storage/mru: Cosmetic changes as per #743 comments

* swarm/storage/mru: refct request encoder/decoder > marshal/unmarshal

* swarm/storage/mru: Cosmetic changes as per review in #748

* swarm/storage/mru: removed timestamp proof placeholder

* swarm/storage/mru: cosmetic/doc/fixes changes as per comments in #704

* swarm/storage/mru: removed unnecessary check in Handler.update

* swarm/storage/mru: Implemented Marshaler/Unmarshaler iface in Request

* swarm/storage/mru: Fixed linter error

* swarm/storage/mru: removed redundant address in signature digest

* swarm/storage/mru: fixed bug: LookupLatestVersionInPeriod not working

* swarm/storage/mru: Unfold Request creation API for create or update+create
set common time source for mru package

* swarm/api/http: fix HandleGetResource error variable shadowed
when requesting a resource that does not exist

* swarm/storage/mru: Add simple check to detect duplicate updates

* swarm/storage/mru: moved Multihash() to the right place.

* cmd/swarm: remove unneeded clientaccountmanager.go

* swarm/storage/mru: Changed some comments as per reviews in #784

* swarm/storage/mru: Made SignedResourceUpdate.GetDigest() public

* swarm/storage/mru: cosmetic changes as per comments in #784

* cmd/swarm: Inverted --multihash flag default

* swarm/storage/mru: removed Verify from SignedResourceUpdate.fromChunk

* swarm/storage/mru: Moved validation code out of serializer
Cosmetic / comment changes

* swarm/storage/mru: Added unit tests for UpdateLookup

* swarm/storage/mru: Increased coverage of metadata serialization

* swarm/storage/mru: Increased test coverage of updateHeader serializers

* swarm/storage/mru: Add resourceUpdate serializer test

* cmd/swarm: add implicit subcommand help (fix #786)

* cmd/swarm: moved implicit help to a recursive func

* cmd/swarm: minor cli flag text adjustments

* cmd/swarm, swarm/storage, swarm: fix  mingw on windows test issues

* cmd/swarm: support for smoke tests on the production swarm cluster

* cmd/swarm/swarm-smoke: simplify cluster logic as per suggestion

* changed colour of landing page

* landing page reacts to enter keypress

* swarm/api/http: sticky footer for swarm landing page using flex

* swarm/api/http: sticky footer for error pages and fix for multiple choices

* swarm: propagate ctx to internal apis (#754)

* swarm/simnet: add basic node/service functions

* swarm/netsim: add buckets for global state and kademlia health check

* swarm/netsim: Use sync.Map as bucket and provide cleanup function for...

* swarm, swarm/netsim: adjust SwarmNetworkTest

* swarm/netsim: fix tests

* swarm: added visualization option to sim net redesign

* swarm/netsim: support multiple services per node

* swarm/netsim: remove redundant return statement

* swarm/netsim: add comments

* swarm: shutdown HTTP in Simulation.Close

* swarm: sim HTTP server timeout

* swarm/netsim: add more simulation methods and peer events examples

* swarm/netsim: add WaitKademlia example

* swarm/netsim: fix comments

* swarm/netsim: terminate peer events goroutines on simulation done

* swarm, swarm/netsim: naming updates

* swarm/netsim: return not healthy kademlias on WaitTillHealthy

* swarm: fix WaitTillHealthy call in testSwarmNetwork

* swarm/netsim: allow bucket to have any type for a key

* swarm: Added snapshots to new netsim

* swarm/netsim: add more tests for bucket

* swarm/netsim: move http related things into separate files

* swarm/netsim: add AddNodeWithService option

* swarm/netsim: add more tests and Start* methods

* swarm/netsim: add peer events and kademlia tests

* swarm/netsim: fix some tests flakiness

* swarm/netsim: improve random nodes selection, fix TestStartStop* tests

* swarm/netsim: remove time measurement from TestClose to avoid flakiness

* swarm/netsim: builder pattern for netsim HTTP server (#773)

* swarm/netsim: add connect related tests

* swarm/netsim: add comment for TestPeerEvents

* swarm: rename netsim package to network/simulation

- AsyncHasher implements AsyncWriter interface
 - add extra level for zerohashes in pool to lookup empty data hash
 - remove unused segment, hash and depth fields from Tree
 - Hash pkg function -> syncHash moved to test
 - add asyncHash helper func to tests using shuffle
 - add TestAsyncCorrectness to tests
 - add BenchmarkBMTAsync to tests
 - refactor benchmarks using subbenchmarks
 - improved comments
 - preinitialise base hashers on the nodes

* ethdb: fix memory database

* core: fix bloombits checking

* core: minor polish

* keystore, ethash, eth, miner, rpc, whisperv6: tech debt with now defunct set.

* whisperv5: swap out gopkg.in/fatih/set.v0 with supported set

* dashboard: fix CSS, escape special HTML chars, clean up code

* dashboard: change 0 to 1

* dashboard: add escape-html npm package

build: Fix a typo in ci.go

* swarm: propagate ctx, enable opentracing

* swarm/tracing: log error when tracing is misconfigured

correct the algorithm in the comments for fakeBlockNumber， from "min" to "max".

* vendor: update leveldb

* ethdb: remove useless warning log

* cmd, dashboard, internal, log, node: logging feature

* cmd, dashboard, internal, log: requested changes

* dashboard, vendor: gofmt, govendor, use vendored file watcher

* dashboard, log: gofmt -s -w, goimports

* dashboard, log: gosimple

* cmd/swarm: minor cli flag text adjustments

* swarm/api/http: sticky footer for swarm landing page using flex

* swarm/api/http: sticky footer for error pages and fix for multiple choices

* cmd/swarm, swarm/storage, swarm: fix  mingw on windows test issues

* cmd/swarm: update description of swarm cmd

* swarm: added network ID test

* cmd/swarm: support for smoke tests on the production swarm cluster

* cmd/swarm/swarm-smoke: simplify cluster logic as per suggestion

* swarm: propagate ctx to internal apis (#754)

* swarm/metrics: collect disk measurements

* swarm/bmt: fix io.Writer interface

  * Write now tolerates arbitrary variable buffers
  * added variable buffer tests
  * Write loop and finalise optimisation
  * refactor / rename
  * add tests for empty input

* swarm/pss: (UPDATE) Generic notifications package (#744)

swarm/pss: Generic package for creating pss notification svcs

* swarm: Adding context to more functions

* swarm/api: change colour of landing page in templates

* swarm/api: change landing page to react to enter keypress

* core: fix func TxDifference

fix a typo in func comment;
change named return to unnamed as there's explicit return in the body

* fix another typo in TxDifference