* Support `pending` block in RPC

* Forward calls from miner to client in case no pending block is available

* removed redundant unwraps

* fixed compilation error, removed warnings

* fixed transaction queue merge conflict

* fixed failing ethminer doc test

* Even more detailed errors for transaction queue

* Small rename

* Removing macros in favour of functions+try!()

* Changing  to wipe-out all transactions from particular sender lower then given nonce.

* Changing given nonce to be client_nonce

* Fixing test_client to support proper nonces when transactions are added to blockchain

* Fixing logic for transactions from new blocks in chain

* spec loading cleanup in progress

* changed engine field in json spec

* refactored engine params

* polishing spec loading refactor

* fixed compiling json tests

* fixed compiling parity

* removed warnings

* removed commented out code

* fixed failing test

* bringing back removed TODO in spec.