This implements a generic approach to enabling soft forks by allowing
anyone to put in hashes of contracts that should not be interacted from.
This will help "The DAO" in their endevour to stop any whithdrawals from
any DAO contract by convincing the mining community to accept their code
hash.
(cherry picked from commit 7a5b571c67)
Added chain configuration options and write out during genesis database
insertion. If no "config" was found, nothing is written to the database.
Configurations are written on a per genesis base. This means
that any chain (which is identified by it's genesis hash) can have their
own chain settings.
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.
The runtime environment can be used for simple basic execution of
contract code without the requirement of setting up a full stack and
operates fully in memory.
