tjger - the java game & entertainment rt Code (Desktop)

Remove playing field entry as playing field system will not ported.

Improve computer opponent.

Improve computer player, setting barrier.

Improve computer player. Missing:
- do not put barrier if (only) player is blocked
- and also not if the way to the most front (if opponent) is blocked
- Sounds depending on the theme

Improve computer player.

Improve computer opponent.

Improve computer opponent.

Fix due to changes in tjger SimpleStatusBar.

Add a state to check whether a game was stopped and allow to inherit from the class that is used for calculate the shortest way for a playing field.

Add new barriercanditates fields and fix the problem that a field can be reached in different ways where one way can have barriers.