Makes pull into a mob verb

And so dies the last of the atom verbs. Anything for a less laggy right click menu. Same deal as with examine and point. The verbs -= /atom/movable/verb/pull I removed weren't actually needed because start_pulling already checks for anchored, so you still can't drag MULEs, chairs and mechas (yes I tested it).
Would be neat if ghosts could point, but have the point inherit the invisibility var from the pointer. So other ghosts can see ghost-points but people can't.