Merge pull request #14 from bsuh/master

Add unit test for infinite recursion in collision detection.
Merge pull request #15 from bsuh/master

Refine testing code, add more tests, fix failing tests
Merge pull request #17 from bsuh/master

improve performance
added user_modules to settings
added random to settings.user_modules
remove temporary recursion fix
added unit test for overlapping robots