shape margins for GJK
small refactor
Updated gjk tests for shape margins
re-enable fix for degenerate GJK cases
Collision masking & groups, closes #33
Line swept shapes, closes #34
Updated quaternion tests
Rename GjkEpa2 -> GjkEpa, NearPhase -> NarrowPhase, RevoluteConstraint -> PointConstraint
Adds linear & angular factors for rigid body velocities, closes #35
Updating mass changes inertia tensor & caching inverted mass, fixes #36
Added MeshShape & examples, closes #18
bump version to 0.7
updated readme