abi: support for input and output slices & removed support for implicit type conversion

p2p: enable EIP-8 handshake sending

cmd/utils, miner: A/B testing JIT VM. Disabled for miners

cmd/geth: add missing gas target flag (fixing 0 convergence issue)

With the Ethereum Homestead fork is now behind us, we can
assume that everyone runs an EIP-8 capable client.

cmd/geth: fix startup with empty database

This prevents display of the warning for --dev and --olympic.

accounts/abi/bind: surface raw wrappers to access low level ops

common: added Hash unmarshal json length validation

This PR introduces a 10% probability that you'll run the client with the
JIT enabled testing the new client and helps us potentially catch
errors when reported.

This feature is **disabled** for miners (disabling the JIT completely).
The JIT can however be force for miners if they enable both --jitvm and
--forcejit.

eth: enforce signing hashes using eth_sign instead of arbitrary data

core: homestead chain configuration & artificial gas floor target mining flag

Exposes some core methods to transition and compute new state
information and adds an additional return value to the transition db
method to fetch required gas for that particular message (excluding gas
refunds from any SSTORE[X] = 0 and SUICIDE.

Fixes #2395

The chain maker and the simulated backend now run with a homestead phase
beginning at block 0 (i.e. there's no frontier).

This commit also fixes up #2388

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.

accounts/abi/bind, cmd/abigen: dedup structs, exclude patterns

eth: fix accidental nil panic on nil errors

eth: manually convert errors to strings on the trace API (json cannot)

accounts/abi/bind: fix double pointer in generated code

accounts/abi/bind: Go ABI binding generator

core, core/vm, tests: changed the initialisation behaviour of the EVM

This commit serves as a temporary workaround for enabling the jit until
the block customisation PR is merged in.