#14 New build system, roofs, terrain save and... cities !

Hi,

I did a lot of changes on the build system, which is now more powerful. It allows square and line selection now with G and F and erasing with H,( I'll remap them later to shift and ctrl).

Also You can now create Cities, and gain territory. 

On the more technical side I've expanded the saving system, which now can save your cities, the resources generated for each maps, and the zones.