This removes the burden on a single object to take care of all
validation and state processing. Now instead the validation is done by
the `core.BlockValidator` (`types.Validator`) that takes care of both
header and uncle validation through the `ValidateBlock` method and state
validation through the `ValidateState` method. The state processing is
done by a new object `core.StateProcessor` (`types.Processor`) and
accepts a new state as input and uses that to process the given block's
transactions (and uncles for rewords) to calculate the state root for
the next block (P_n + 1).

cmd/geth, cmd/utils: surface the light KDF flag to the CLI

rpc/api: fix #1972 api regression (nil eth panic) in attach

event/filter: fix data race in the test

eth: fix error casting regression during database open

cmd/geth: fix recover command crash if no param is supplied

whisper: fix datarace in expiration test

jsre: fix #1876, sleep too short on a slow test server

tests: fix data race in bad-block-report disabling during tests

eth/downloader: fix dysfunctional ignore list hidden by generic set

eth, p2p, rpc/api: polish protocol info gathering

accounts/abi: ABI fixes & added types

Infinite loop in filters

crypto/secp256k1: add C compiler flags for pkgsrc

pkgsrc is a cross-platform package manager that also
supports OS X.

miner: synchronise start / stop

This PR fixes an issue where the remote worker was stopped twice and not
properly handled. This adds a synchronised running check to the start
and stop methods preventing closing of a channel more than once.

eth: added new testnet peers

cmd/geth, cmd/utils, eth: group CLI flags by purpose

Godeps: upgrade github.com/huin/goupnp

Changed field `input` to new `inputs`. Addad Hash and Address as input
types.

Added bytes[N] and N validation

Fix for xeth OOM issue

There are a bunch of changes required to make this work:

- in miner: allow unregistering agents, fix RemoteAgent.Stop
- in eth/filters: make FilterSystem.Stop not crash
- in rpc/comms: move listen loop to platform-independent code

Fixes #1930. I ran the shell loop there for a few minutes and didn't see
any changes in the memory profile.

Argument parsing can lead to panic in rpc channel

eth: don't block sync goroutines that short circuit