Limit number of units

[namelessvoid]

Set a limitation to the number of units in StartWindow so there are not more units than squares on the board.

One idea:
Units per player = floor (board height * widht / 2)

[namelessvoid]

Moved to milestone 0.2 Development

I will think about it again in version 0.2 because I ran into a problem:
The board is only initialized if "Start Game" was clicked so the maximum unit count is not available while StartGameWindow is visible.

This can only be resolved by restructuring the game set up process which will be changed in version 0.2 anyway.