Revert "BulletSim: Add logic to linksets to change physical properties for"
The changes don't seem to be ready for prime time.

This reverts commit b44f0e1a00eba7f76401692322e48a3b23a81164.
Revert "BulletSim: change BSDynamics to expect to be passed a BSPrimLinkable"
The changes don't seem to be ready for prime time.

This reverts commit d0d654e2186c8b81c1150da89a549e4f7162a2b4.
Revert "BulletSim: only create vehicle prim actor when vehicles are enabled."
The changes don't seem to be ready for prime time.

This reverts commit acb7b4a09ad564d1dfae3ad12adbb593ca3942c9.
Revert "BulletSim: move collision processing for linksets from BSPrimLinkable"
The changes don't seem to be ready for prime time.

This reverts commit b4c3a791aa55390bff071b3fe4bbe70c1d252703.
Revert "Add experimental stubs for an extension function interface on both"
The changes don't seem to be ready for prime time.

This reverts commit 13a4a80b3893af13ab748c177b731fed813974ca.
Revert "BulletSim: freshen up the code for constraint based linksets."
The changes don't seem to be ready for prime time.

This reverts commit 803632f8f32d91bb4aec678d8b45a8430c2703e1.