* Minor additions to allow resetting of code.

* Add test.

* Introduce options for fine-grained management of work queue.

- Minimum reseal period between non-mandatory (transaction) reseals.
- Maximum historical cached block size.

Defaults changed to reflect real-world scenarios (2s, 20 blocks).

* Fix test bug.

* 50 -> 20.

* Ensure we don't reject our own transactions for gasprice.

* Add test.

* verifier is no longer a template type of client

* added missing ,

Also Move the gas limit into the transaction queue from the miner.

- Optional limit for the amount of gas transactions may have;
- option to restruct transactions returned/queried to only those
which have been executed.

* replace deprecated hashdb method names

* spaces -> tabs

Rather than just the canon chain.

Rather than just the canon chain.

* Introduce whitelist for softfork

* Use extradata for fork id.

* Fix condition.

* Removing old transactions

* Explanation comment [ci skip]