Fixes #3608

consensus/ethash: simplify concurrency in VerifyHeaders

Currently http cors and websocket origins are a comma separated string in the
config object. These are replaced with string arrays that are more expressive in
case of a config file.

This change removes a convoluted use of sync/atomic from VerifyHeaders.
It also fixes the annoying error about future blocks.

The genesis block doesn't have a valid ancestor.

cmd/rlpdump: support dumping only the first entity

* p2p/discover, p2p/discv5: add marshaling methods to Node

* p2p/netutil: make Netlist decodable from TOML

* common/math: encode nil HexOrDecimal256 as 0x0

* cmd/geth: add --config file flag

* cmd/geth: add missing license header

* eth: prettify Config again, fix tests

* eth: use gasprice.Config instead of duplicating its fields

* eth/gasprice: hide nil default from dumpconfig output

* cmd/geth: hide genesis block in dumpconfig output

* node: make tests compile

* console: fix tests

* cmd/geth: make TOML keys look exactly like Go struct fields

* p2p: use discovery by default

This makes the zero Config slightly more useful. It also fixes package
node tests because Node detects reuse of the datadir through the
NodeDatabase.

* cmd/geth: make ethstats URL settable through config file

* cmd/faucet: fix configuration

* cmd/geth: dedup attach tests

* eth: add comment for DefaultConfig

* eth: pass downloader.SyncMode in Config

This removes the FastSync, LightSync flags in favour of a more
general SyncMode flag.

* cmd/utils: remove jitvm flags

* cmd/utils: make mutually exclusive flag error prettier

It now reads:

   Fatal: flags --dev, --testnet can't be used at the same time

* p2p: fix typo

* node: add DefaultConfig, use it for geth

* mobile: add missing NoDiscovery option

* cmd/utils: drop MakeNode

This exposed a couple of places that needed to be updated to use
node.DefaultConfig.

* node: fix typo

* eth: make fast sync the default mode

* cmd/utils: remove IPCApiFlag (unused)

* node: remove default IPC path

Set it in the frontends instead.

* cmd/geth: add --syncmode

* cmd/utils: make --ipcdisable and --ipcpath mutually exclusive

* cmd/utils: don't enable WS, HTTP when setting addr

* cmd/utils: fix --identity

cmd/puppeth: format dashboard html, update syncmode flags

* consensus, core, ethstats: use engine specific block beneficiary

* core, eth, les, miner: use explicit beneficiary during mining

* consensus/clique, internal/web3ext: support hash based API queries

* consensus/clique: make RPC return types public

internal/ethapi: Add support for fetching information about the current call in JS traces

- Moved fuse related code in a new package, swarm/fuse
- Added write support
  - Create new files
  - Delete existing files
  - Append to files (with limitations)
- More test coverage

This PR is a prototype implementation of plugable consensus engines and the
Clique PoA protocol ethereum/EIPs#225

eth: announce block after sync cycle (star topology)

* whisper: GetMessages fixed; size restriction updated
* whisper: made PoW and MaxMsgSize customizable
* whisper: test added
* whisper: sym key management changed
* whisper: identity management refactored
* whisper: API refactoring (Post and Filter)
* whisper: big refactoring complete
* whisper: spelling fix
* whisper: variable topic size allowed for a filter
* whisper: final update
* whisper: formatting
* whisper: file exchange introduced in wnode
* whisper: bugfix
* whisper: API updated + new tests
* whisper: statistics updated
* whisper: wnode server updated
* whisper: allowed filtering for variable topic size
* whisper: tests added
* whisper: resolving merge conflicts
* whisper: refactoring (documenting mostly)
* whsiper: tests fixed
* whisper: down cased error messages
* whisper: documenting the API functions
* whisper: logging fixed
* whisper: fixed wnode parameters
* whisper: logs fixed (typos)

travis, appveyor: update to Go 1.8.1

consensus/ethash, eth: don't mine if 0 threads are set

all: clean up various error handling in core and the miner

This PR deprecates the file related RPC calls in favour of an improved HTTP API.

The main aim is to expose a simple to use API which can be consumed by thin
clients (e.g. curl and HTML forms) without the need for complex logic (e.g.
manipulating prefix trie manifests).

* cmd, les, eth, eth/gasprice: using new gas price oracle

* eth/gasprice: renamed source file

* eth/gasprice: added security checks for gpo params

* eth/gasprice: fixed naming issues

* eth/gasprice: max limit, maxEmpty

- intended to be a swarm alternative to termbin.com
- added --stdin flag to swarm executable. if set, swarm will
  read data from stdin and postRaw it.

This commit adds a build step to travis to auto-delete unstable archives older than
14 days (our regular release schedule) from Azure via ci.go purge.

The commit also pulls in the latest Azure storage code, also switching over from
the old import path (github.com/Azure/azure-sdk-for-go) to the new split one
(github.com/Azure/azure-storage-go).