Remove testClosestDistance

This is superceded by the various collisionDetect<shape>Tests and
collisionDetectGradTest.
Remove testCollisionGrad.

This has been replaced by the much cleaner collisionDetectGradTest
Remove closest(Distance|Points)AllBodies

These have been replaced by closestDistance and collisionDetect respectively.
Add support for active_collision_options.body_idx

Still no support for active_collision_options.collision_groups.