Added missing license headers
Tileset loads it's own file, deleted libs directory

I only had to move vector2.hpp; the rest was pointless. I think this
directory structure was caused by my originally intending to make this
editor inside Tortuga's repo.
Now using the singleton pattern for Map

This is because it'd be a pain to access the map object from lua
otherwise. Plus, since there will only ever be one map, the conversion
went pretty smoothly.