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).

* Makefile: fix devtools target

* core: regenerate genesis marshaling with fjl/gencodec@cbfa5be5a8a8

* core/types: regenerate marshaling methods with fjl/gencodec@cbfa5be5a8a8

* core/types: add "hash" to JSON headers

* debug: Converted uint64-blocknumber into rpc.Blocknumber

* api/debug: Fix pending block issues in DumpBlock

In `touch` operation, only `touched` filed has been changed. Therefore
in the related undo function, only `touched` field should be reverted.
In addition, whether remove this obj from dirty map should depend on
prevDirty flag.

This adds a swarm ls command which lists files and directories stored in a
manifest. Rather than listing all files, it uses "directory prefixes" in case there are a
lot of files in a manifest but you just want to traverse it.

This also includes some refactoring to the tests and the introduction of a
swarm/api/client package to make things easier to test.

This commit adds pluggable consensus engines to go-ethereum. In short, it
introduces a generic consensus interface, and refactors the entire codebase to
use this interface.

ethstats: sanity check ethstats history queries

* swarm/api: fix build/tests on unsupported platforms

Skip FUSE tests if FUSE is unavailable and change build constraints so
the 'lesser' platforms aren't mentioned explicitly. The test are
compiled on all platforms to prevent regressions in _fallback.go

Also gofmt -w -s because why not.

* internal/web3ext: fix swarmfs wrappers

Remove inputFormatter specifications so users get an error
when passing the wrong number of arguments.

* swarm/api: improve FUSE-related logging and APIs

The API now returns JSON objects instead of strings.
Log messages for invalid arguments are removed.

ethstats: work around weird URL scheme parsing issues

Fixes #3792 by stripping debug symbols.

core, core/types: use non-pointer receiver for Marshal* methods

accounts/usbwallet: fix Ledger hidapi/libusb protocol violation

Regenerated with fjl/gencodec@1a75a2161009
Also add ,omitempty to optional GenesisAccount fields.

core/types: ensure all EIP155 signer fields are set by deriveSigner

Fixes #3819

build: unify vendor skipping, always run go vet

This ensures 'make test' finds all errors that remote CI would find.
Go 1.7 vet reports a false positive in package log, add a workaround.

core: refactor genesis handling

This commit solves several issues concerning the genesis block:

* Genesis/ChainConfig loading was handled by cmd/geth code. This left
  library users in the cold. They could specify a JSON-encoded
  string and overwrite the config, but didn't get any of the additional
  checks performed by geth.
* Decoding and writing of genesis JSON was conflated in
  WriteGenesisBlock. This made it a lot harder to embed the genesis
  block into the forthcoming config file loader. This commit changes
  things so there is a single Genesis type that represents genesis
  blocks. All uses of Write*Genesis* are changed to use the new type
  instead.
* If the chain config supplied by the user was incompatible with the
  current chain (i.e. the chain had already advanced beyond a scheduled
  fork), it got overwritten. This is not an issue in practice because
  previous forks have always had the highest total difficulty. It might
  matter in the future though. The new code reverts the local chain to
  the point of the fork when upgrading configuration.

The change to genesis block data removes compression library
dependencies from package core.

All uses of ChainConfig.ChainId eventually end up in NewEIP155Signer.
This fixes the case where users forget to set the ChainId in their
config.