supertux: config: use os.mkdir()

Use os.mkdir(), os.path.mkdir() doesn't exist.
Merge pull request #1 from maxanton/feature/python+os_mkdir

supertux: config: use os.mkdir()
Moved non-working Stroke/Dab/SketchLayer/... to flexlay/wip/ so they don't get in the way
Cleaned up flexlay/, it's now pylint-clean
Fixed a few pylint warnings in supertux/
Keep track of pylint state and don't recompute it each time scons is run
Removed SuperTux v1 saving, it's not working at moment and probably of little use
Use proper Mock object in unittest instead of handbuild closures
Final round of pylint fixes, supertux/ is now clean
Split TileMapPaintTool into separate tools for left and right mouse button and fixed some Tool errors
Fixed drag&drop of game objects
Some twiggling around with __main__.py
Fixed TileSelector resizing
Fixed some issues in the TileSelectorWidget
Switched from PyQt5 to PyQt4 for better compatibility with Mac and Windows
Fixed coordinate translation on object drop
Added missing 'virtual' functions to ObjMapObject
Draw bounding rect on top of other stuff
Removed a lot of noise print() stuff
Some quick&dirty workarounds for sexpr parsing issues, needs a better fix