eth: don't accept transactions until we sync up with the network

eth/downloader: adaptive quality of service tuning

eth/downloader: make fast sync resilient to critical section fails

core: add missing lock in TxPool.GetTransaction

Fixes #2650

cmd/geth: make console tests more robust

* use --port 0 to avoid p2p port conflicts
* use --maxpeers 0 so it doesn't connect to bootstrap nodes
* use geth.expectExit() to wait for termination

This makes "geth js file.js" terminate again.

eth/downloader: ensure cancel channel is closed post sync

eth/downloader, trie: pull head state concurrently with chain

cmd, console: split off the console into a reusable package

core, core/state, trie: enterprise hand-tuned multi-level caching

core/state: return the starting nonce for non-existent accs (testnet)

eth: enable bad block reports

misc: fix spelling mistake

eth/api: fixed GetCompilers when there is no error creating Solc

common/compiler: support relative path to solc

We used to have reporting of bad blocks, but it was disabled
before the Frontier release. We need it back because users
are usually unable to provide the full RLP data of a bad
block when it occurs.

A shortcoming of this particular implementation is that the
origin peer is not tracked for blocks received during eth/63
sync. No origin peer info is still better than no report at
all though.

README: make it clear how to build all executables

eth: add new RPC method (personal.) SignAndSendTransaction

core: Simplify bloom9 tests

eth/filter: bugfix which can cause a nil pointer crash when parsing f…