The most visible change is event-based dialing, which should be an
improvement over the timer-based system that we have at the moment.
The dialer gets a chance to compute new tasks whenever peers change or
dials complete. This is better than checking peers on a timer because
dials happen faster. The dialer can now make more precise decisions
about whom to dial based on the peer set and we can test those
decisions without actually opening any sockets.

Peer management is easier to test because the tests can inject
connections at checkpoints (after enc handshake, after protocol
handshake).

Most of the handshake stuff is now part of the RLPx code. It could be
exported or move to its own package because it is no longer entangled
with Server logic.

The previous limit was 10MB which is unacceptable for all kinds
of reasons, the most important one being that we don't want to
allow the remote side to make us allocate 10MB at handshake time.

p2p/discover: evacuate self from node database during iterations

core/vm, rpc: added disasm to `ext_` RPC

core: added RPC sign back in

Add StateTests/RandomTests and VMTests/RandomTests

make registrar available in console

automatic DAG pregeneration for smooth epoch transitions

Fix two additional download vulnerabilities

- backend: AutoDAG bool flag passed from cli/eth.Config to ethereum, autoDAG loop started if true
- backend: autoDAG loop start/stop, remove previous DAG
- cli: AutoDAG bool flag, off by default, but automatically ON if mining
- admin jsre: add startAutoDAG stopAutoDAG and makeDAG in miner section
- switch on/off DAG autogeneration when miner started/stopped on console

prefix dapp key/value entries in extradb

Tests updates

Cleanup

core/vm: optimisation on RETURN and updated tests

Storing tx receipts in extraDb

CLI, JSRE admin and  Solc improvements 

eth/downloader: fix test to it doesn't time out on a slow machine