Added a physics context ("World")
Added a physical placeholder player that can be moved around and interacts with other physics objects, including the ground
Added a camera that can follow other objects around
	- springy behavior
	- will be useful to have this abstraction for making a level editor
Added a util class, added a distance function
added an editor class, currently empty

Modified main.lua to support these new features
Merge branch 'master' of https://github.com/tie372/overgrowth

Conflicts:
	main.lua