* Change coinbase maturity to 240 blocks in most cases, with main/test early chains allowing 30 blocks. I've kept the 240 consistent in regtest to avoid having to redesign a lot of the test cases.
* Disabled mining unit test which require COINBASE_MATURITY worth of pre-calculated blocks, as we'd otherwise be constantly refactoring them.
* Moved functional test which uses the Bitcoin testnet block data as its reference, as it completely breaks as we introduce Dogecoin data.
* Updated standard blockchains for tests from 100/200 to 240/480 as appropriate.
Calling getblocktemplate without the segwit rule specified is most
likely a client error, since it results in lower fees for the miner.
Prevent this client error by failing getblocktemplate if called without
the segwit rule specified.
