Added Entity.maxVel support.
TODO item marked as complete.
Added Entity.bounciness support.
TODO item marked as complete.
Ensure entities are pulled by gravity on first world step.
Push contact events to contact buffer.
Removed comment.
Merge branch 'test'
Added Entity.check, checkAgainst, type, collideWith, and handleMovementTrace support.
EndContact not needed because BeginContact is persistent.
Prevent Impact from doing its own collision checks.
Added completed TODO items.