Clean move / attack code

[VedVid]

For example, MoveOrAttack and Move and Attack should take similar set of arguments. But now some functions takes coordinations, other uses *Creature, etc.

[VedVid]

After some thinking, I'm fine with this. Passing integers like target_x and target_y to move-related functions is much more universal than passing Tile or Creature. Dev can pass position of whatever he want - tile, creature, object...

Another thing, I'm a bit less sure about, is attack. For now, player can attack only creatures, but what if we would like to implement destructible environment? I don't think that creating destructible walls as creatures with NoAI is pretty.

[VedVid]

Created new issue #40 to adress doubts from previous post. Now, this issue can be closed safely.