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.

transferdev/Transfercoin,syfares/Transfercoin,aspaas/ion,aspaas/ion,bryceweiner/mojocoin,Infernoman/Transfercoin,bryceweiner/mojocoin,MinuteManReserve/mmr-core,aspaas/ion,Infernoman/Transfercoin,bryceweiner/mojocoin,transferdev/Transfercoin,syfares/Transfercoin,transferdev/Transfercoin,syfares/Transfercoin,bryceweiner/mojocoin,aspaas/ion,transferdev/Transfercoin,Infernoman/Transfercoin,Infernoman/Transfercoin,Infernoman/Transfercoin,syfares/Transfercoin,transferdev/Transfercoin,bryceweiner/mojocoin,transferdev/Transfercoin,MinuteManReserve/mmr-core,MinuteManReserve/mmr-core,aspaas/ion,MinuteManReserve/mmr-core,syfares/Transfercoin,MinuteManReserve/mmr-core,Infernoman/Transfercoin,bryceweiner/mojocoin,aspaas/ion,syfares/Transfercoin