Fixed transaction lists in QT and RPC when POS blocks are generated by user.

Modified the transaction list in the the QT interface to display
interest from Proof Of Stake blocks.  Also added "Stake interest"
search option in the Transactions tab so people can see a list of
of their interest earned from their proof of stake blocks.

Note 1: You can now export all transactions to a CSV file and get a
total using Excel and the total will equal your wallet balance!
Note 2: No wallet rescan is required for this fix.

Also fixed the RPC commands listtransactions, listaccounts and getinfo.
These commands now report accurate totals when POS blocks are
generated by the user. "newmint" in getinfo now includes immature
proof of stake interest.