Influence Maps

The influence maps used for calculating migration/colonization is now mostly implemented. It works in calculating influence from systems and fleets, but I think it's a bit too strong at the moment. I will have to tweak it until it feels right.

Why is influence maps important? They serve many purposes, which I will list:

1. The highest two influences on one grid cell means those two empires are in contact. If no influence between the two empires overlap anywhere, then they're not in contact. You can get in contact by moving some ships near their influence, because your ships will extert some influence.

2. AI calculations. AI now can see if you're pushing against it, especially if you create a massive fleet which will have a lot of influence, and can plan accordingly.

3. Colonization/Migration. When an unoccupied star's grid cells are all dominated by an empire's influence, that empire can now have its people migrate to the system, provided that it's explored

4. Quick overview of your empire's terrority and nearby empires' terrorities.

Now that the influence map are mostly done (just need optimizations and influence strength tweaking, along with fixing the center of circles), the next item on agenda is the migration/colonization code.

Here's a screenshot of the influence map, it's a bit ugly at the moment. I'll have to figure out a way to make it look nice, but that's low on list of priorities. You can see some empires on top left that's close to each other, pushing against each other's influence.