Porting over hotkeys for adding rigidbody objects (from original branch)

* Ctrl-R          = Add Active
* Ctrl-Shift-R = Add Passive
* Ctrl-Alt-R    = Remove


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54105 954f8c5b-7b00-dc11-b283-0030488c597c