Trie stuff.
Minor fix and some part-finished work on Trie.
TrieDB framework and insertion.
LevelDB overlay and map backends.
TrieDB remove nodes and tests.
Iterator beginnings.
Merge branch 'master' of https://github.com/programmerTim/cpp-ethereum into programmerTim-master

Conflicts:
	libethereum/BlockInfo.cpp
	libethereum/Trie.h
	test/main.cpp
Iterators in the TrieDB!
Repotted a lot of the Trie stuff.
Cleanups and preparation.
Minor fix for keeping trie clean.
Repotted tests.
Caching (on two levels!) and quite possibly working State transition
class.
Fake dagger, and moves to test the state transitions.
Various fixes.
Working state-transition test.
State updater tested and working pretty well.
Peer network code NYW.
Basic P2P functionality.
Pinging.
Added client API & prototypal GUI.