Added RPC call 'getmemorypool' that provides everything needed to construct a block with a custom generation transaction and submit a solution
getmemorypool [data]
If [data] is not specified, returns data needed to construct a block to work on:
"version" : block version "previousblockhash" : hash of current highest block "transactions" : contents of non-coinbase transactions that should be included in the next block "coinbasevalue" : maximum allowable input to coinbase transaction, including the generation award and transaction fees "time" : timestamp appropriate for next block "bits" : compressed target of next block
If [data] is specified, tries to solve the block and returns true if it was successful.