sequencer gaps
- remove unneeded checks (poll checks editor is non-null)
- use booleans
- rename operator SEQUENCER_OT_gap_remove, _gap_insert

also quiet shadow warning in rigidbody.c (shadowing 'loc')


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55604 954f8c5b-7b00-dc11-b283-0030488c597c