More DB additions (issue #125). Fixed small bug.

- Added CardGame.saveDBPlayerBanking() to store all banking transactions
  to the stats DB
- Added "migrate" command to allow one-step migration of player.txt data
  to stats.sqlite3
- Added "transaction" property for Player
- Changed max output string length for "query" command to 300 characters
- Added an "id" field to the Banking table of the stats DB
- Fixed bug in TexasPoker where if every player except one folds pre-flop,
  each player's hand is revealed anyways (from ad9a51ab)