The EVM is now initialised with an additional configured object that
allows you to turn on debugging options.

The EVM was previously initialised and created for every CALL, CALLCODE,
DELEGATECALL and CREATE. This PR changes this behaviour so that the same
EVM can be used through the session and beyond as long as the
Environment sticks around.

Added a future lock which prevents the anything being added or removed
from or to the set when looping over the set of blocks. This fixes a nil
pointer in the range loop when trying to retrieve a block from the set
which was previously available but removed due to regular chain
processing.

Fixes #2305

Previously all blocks that were already in our chain were never re
announced as potential uncle block (e.g. ChainSideEvent). This is
problematic during mining where you want to gather as much possible
uncles as possible increasing the profit. This is now addressed in this
PR where during reorganisations of chains the old chain is regarded as
uncles.

Fixed #2298

As we aren't really using the standarized SHA-3

Assuming the following scenario where a miner has 15% of all hashing
power and the ability to exert a moderate control over the network to
the point where if the attacker sees a message A, it can't stop A from
propagating, but what it **can** do is send a message B and ensure that
most nodes see B before A. The attacker can then selfish mine and
augment selfish mining strategy by giving his own blocks an advantage.

This change makes the time at which a block is received less relevant
and so the level of control an attacker has over the network no longer
makes a difference.

This change changes the current td algorithm `B_td > C_td` to the new
algorithm `B_td > C_td || B_td == C_td && rnd < 0.5`.

* Removed some strange code that didn't apply state reverting properly
* Refactored code setting from vm & state transition to the executioner
* Updated tests

* change gas cost for contract creating txs
* invalidate signature with s value greater than secp256k1 N / 2
* OOG contract creation if not enough gas to store code
* new difficulty adjustment algorithm
* new DELEGATECALL op code

Pending logs are now filterable through the Go API. Filter API changed
such that each filter type has it's own bucket and adding filter
explicitly requires you specify the bucket to put it in.

Implemented `runtime.Call` which uses - unlike Execute - the given state
for the execution and the address of the contract you wish to execute.
Unlike `Execute`, `Call` requires a config.

Integrated code review suggestions

Integrated last review comments

In order to make this happen, kill all remaining trivial uses of
common/{rlp,value}.go. The non-trivial ones have been updated earlier.

The test chain generated by makeChainFork included invalid uncle
headers, crashing the generator during the state commit.

The headers were invalid because they used the iteration counter as the
block number, even though makeChainFork uses a block with number > 0 as
the parent. Fix this by introducing BlockGen.Number, which allows
accessing the actual number of the block being generated.

When a chain reorganisation occurs we collect the logs that were deleted
during the chain reorganisation. The removed logs are posted to the
event mux indicating that those were deleted during the reorg.