Add CTxUndo: transaction undo information
Add CTxUndo: transaction undo information

The CTxUndo class encapsulates data necessary to undo the effects of
a transaction on the txout set, namely the previous outputs consumed
by it (script + amount), and potentially transaction meta-data when
it is spent entirely.

Infernoman/crowncoin,dobbscoin/dobbscoin-source,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,Earlz/dobbscoin-source,Earlz/dobbscoin-source,Infernoman/crowncoin,dobbscoin/dobbscoin-source,Infernoman/crowncoin,syscoin/syscoin,Crowndev/crowncoin,syscoin/syscoin,Earlz/dobbscoin-source,Infernoman/crowncoin,Infernoman/crowncoin,Earlz/dobbscoin-source,domob1812/crowncoin,syscoin/syscoin,Earlz/dobbscoin-source,syscoin/syscoin,domob1812/crowncoin,dobbscoin/dobbscoin-source,dobbscoin/dobbscoin-source,domob1812/crowncoin,Crowndev/crowncoin,Crowndev/crowncoin,dobbscoin/dobbscoin-source,Crowndev/crowncoin,dobbscoin/dobbscoin-source,Crowndev/crowncoin,domob1812/crowncoin,Earlz/dobbscoin-source,Crowndev/crowncoin,domob1812/crowncoin,Infernoman/crowncoin,domob1812/crowncoin,syscoin/syscoin