* Add Ethereum Classic support
(Rename homestead-dogmatic -> classic)
* Additional change needed.
* More needed changes.
* Separate database path for known forks.
* Address minor grumble.
* Minor additions to allow resetting of code.
* Add test.
* Provisional DAO hard-fork proposal.
* Change to reflect latest HF spec.
* Include extradata restrictions and overrides.
* Introduce new tests.
* Update tests to new spec format.
* Allow JSON chain spec fields to be optional.
* Remove superfluous definitions. Fix overflow risk.
* Fix build.
* Add missing file.
* Remove old flag.
* Update to latest address set.
* Update tests and test spec to latest.
Change the mining default to release only on own transactions.
Soft-fork will remain default behaviour, but you can now disable
either the whole mechanism (you'll lose money if you mine with this
when the majority network doesn't) or just vote against it but
otherwise go with the flow.
