Merge pull request #33 from mkirk8/master

adding the removal of stranded triangles,
updated gravity
updated gravity
updated gravity to work with groups of triangles stuck together by fixed joints. i left a example of it in game scene. feel free to delete it.
forgot file
Merge pull request #34 from JeremyKooper/master

finalized gravity
Added the Ability to Create user levels. Also gave the Level Loader the ability to create coloured triangles