Minor AI update

The new AI is still pretty easy to beat, but it's different under the hood, with a better overall strategy than before, but also prone to making some dumb mistakes that the previous one didn't. 

I've pulled all the numbers that calculate strategic values for each position out of code and put them into a set of weights that it can modify. The plan is to have it eventually find better strategies by playing against itself with modified weights, but it needs a better set of inputs first. 

I'm also considering a major rule change where capturing zones gives you extra turns, so I'm holding off on training the AI until the final rules are decided.