Partial fix for issue #141.

Make the minimum raise/bet always equal to big blind. Does not solve the
issue of pre-flop negative amounts to call.
Major changes related to issue #139.

- Implemented game states for poker games
- Added "last" and "flast" commands (issue #140)
- Changed "In-play" to "Pot" for player turn messages in poker
- Removed usage of deprecated state variables from poker games
- Updated titles for community cards output
- Fixes for issues #141, #143
- Began phase out of state variables in Blackjack and CardGame
- Updated a couple of strings in strlib