AI meta data

Work done to make AI supportpower usage slightly smarter. Refer to #5830 

Allows some basic usage rules to be defined in yaml for supportpowers.
A better idea would be to divide this into coarse and fine scans.
- Divide the map into boxes of size X by X, where X can be defined on the power (refer to ActorMap to see how to do this).
- For each box, use `ActorMap.ActorsInBox(WPos, WPos)` to fetch all the actors within the box and calculate the attractiveness.
- For the most attractive box, loop over the box to find the most attractive actor, and fire at that.