State and receipt deliveries from a previous eth/62+ sync can hang if
the downloader has moved on to syncing with eth/61. Fix this by also
draining the eth/63 channels while waiting for eth/61 data.

A nicer solution would be to take care of the channels in a central
place, but that would involve a major rewrite.

Unexpected deliveries could block indefinitely if they arrived at the
right time. The fix is to ensure that the cancellation channel is
always closed when the sync ends, unblocking any deliveries. Also remove
the atomic check for whether a sync is currently running because it
doesn't help and can be misleading.

Cancelling always seems to break the tests though. The downloader
spawned d.process whenever new data arrived, making it somewhat hard to
track when block processing was actually done. Fix this by running
d.process in a dedicated goroutine that is tied to the lifecycle of the
sync. d.process gets notified of new work by the queue instead of being
invoked all the time. This removes a ton of weird workaround code,
including a hairy use of atomic CAS.

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