Use EraseBadMoveTransactions() for name_clean.
Merge pull request #74 from domob1812/doublespend

Use EraseBadMoveTransactions() for name_clean.
Merge pull request #76 from domob1812/prune-namelist

Encapsulate CNameDB interface and improve name_list.
Remove GetTxOfNameAtHeight and its usage.

Only use CreateGameTransactions when actually connecting new blocks
(when it is necessary).  This allows us to get rid of
GetTxOfNameAtHeight without replacement, which in turn makes name
pruning easier in the future.