Loading of maps

I added the ability to load maps. The maps are stored in a simple XML file format. The basic.xml map has comments so that no one will ever be confused on how it works.

The code actually turned out to be quite simple. It is weird but I got it all working with only 3 or 4 tests. Python is a really good language to try new stuff in.

I also changed the way hexes are rendered. I did a simple thing by changing the colors of the hexes based on their terrain. This will not be permanent of course.

If anyone is interested, I need some skins for the hexes.