Token Limit on places

[Lazuliert]

Fixed a bug when undoing a AddTokenCommand on a already maxed out place. The undo would remove a token when the AddTokenCommand actually did nothing Now the undo put the old value (which can be seen as doing nothing in that case) Maybe some possible amelioration would be to make the +1 token tool unavailable on maxed out places (with visual effects similar to those on transitions)