Now formats based on underlying hexdata or hexnum type. Fields directly
with respective constructors that cover from native types

Benefits from automatic output formatting differences between
quantities and data

Update Go bootnode address

Correct gas limit validation according to new algorithm

* Use absolute value of (block's gas limit) - (parent's gas limit)
  in comparison with diff limit.
* Ensure the diff is strictly smaller than the allowed size.

Conflicts:
	rpc/api.go

RPC Args

* CALLDATA use getData
* removed old context get range value
* removed casting big => int for some cases
* pc now big int #457

Minor fix

Update README.md