Add CCoins: pruned list of transaction outputs
Add CCoins: pruned list of transaction outputs

The CCoins class represents a pruned set of transaction outputs from
a given transaction. It only retains information about its height in
the block chain, whether it was a coinbase transaction, and its
unspent outputs (script + amount).

It has a custom serializer that has very low redundancy.

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