Until this commit, when sending an RPC request that called `NewEVM`, a blank `vm.Config`
would be taken so as to set some options, based on the default configuration. If some extra
configuration switches were passed to the blockchain, those would be ignored.
This PR adds a function to get the config from the blockchain, and this is what is now used
for RPC calls.
Some subsequent changes need to be made, see https://github.com/ethereum/go-ethereum/pull/17955#pullrequestreview-182237244
for the details of the discussion.
Makes Interface interface a bit more stateless and abstract.
Obviously this change is dictated by EVMC design. The EVMC tries to keep the responsibility for EVM features totally inside the VMs, if feasible. This makes VM "stateless" because VM does not need to pass any information between executions, all information is included in parameters of the execute function.
Paweł Bylica