Don't use submodules. They suck big-time.
Squashed 'PyTMX/' content from commit 917ea58

git-subtree-dir: PyTMX
git-subtree-split: 917ea58d40246987380174d0f436a18de125d044
Merge commit 'a14c558fe9dc770aa75ced60f2ea1139dddd4a64' as 'PyTMX'