Add IEnumerable overload for AddCoins()
Merge branch 'AddCoinEnumerable' into work
Merge branch 'master2' into work
Add Coin(Transaction, outputIndex) convenience ctr
Merge pull request #22 from dthorpe/Coin_Ctr_Tx

Coin(Transaction, index)
Add ctrs to AssetId and Asset to streamline asset issuance given source key or address
Merge pull request #24 from dthorpe/AssetId_ctr

Add ctrs to AssetId and Asset