Implement PvP battles

[GutZuFusss]

Just dropping this draft here to be sure no work is done twice.

Probably most of this is trash, but maybe there is something useful here.

[GutZuFusss]

I am actually surprised how well this works. Everything except necro works perfect already, necro will be a little painful to reverse probably, but also something that is useful despite the garbage code I produced here.

In my defense, I absolutely hate how I handeled the construction of the battle turns, but the lib was obviously more about calculating chances then whatever this is...

If you have a good idea on how to do that better (especially getting rid of the awful state transfer via these fucking "msg_" prefixed variables) without rewriting the simulation API entirely, I'd love to hear.