Battle system

As the title says, adds a partly working battle system :).
Please don't merge it yet. I just ask you to test (and crash) it *g*

Missing features I will NOT implement in this version:
Battle Commands: Link to event, Defend, Double attack
Enemies: Escape, Defend, Charge Up, Self destruct
Different battle layouts (RPG2k3 only)
Handling conditions (Except Dead)
Properly working Event interpreter