Log conflicts on connect block
Merge pull request #91 from aalness/master

Log conflicts on connect block
Add preliminary support for Dogecoin.

Added Dogecoin network protocol version numbers and pre-Digibyte support for Dogecoin difficulty calculations.
Initial draft of calculations post-Digibyte are in place, but untested and commented out. Placeholder
inserted for AuxPoW handling.
Add Dogecoin difficulty hardforks

This adds the code to handle Digishield difficulty calculations for Dogecoin,
as well as correctly setting the switch-over block for when Dogecoin's testnet
difficulty calculations change to enable resets.
Corrected target time for Dogecoin post the Digishield switchover block.
Added initial draft of AuxPoW handling, primarily for Dogecoin at this time however
any chain following the Namecoin merged mining specification should work. AuxPoW blocks
are now identified, and the AuxPoW data validated and checked against the difficulty of
that block.