[Soc-2012-dev] Weekly progress report 3 - Bullet Integration

[Sergej Reich]

This week I:

* Finally got around committing bullet update.
* Removed ability to add multiple rigid body worlds to a scene.
* Added deactivation of rigid bodies.
* Added point cache support for rigid bodies
  (it's not hooked up yet though, see below)
* Fixed calculation of capsule shapes.
* Added units for rigid body properties.
* Fixed a couple of small rigid body update issues.

While point cache works ok now, there are issues with it not being
invalidated properly.
Also the way the simulation is stepped and rebuilt needs changing, we
should remove old hacks and workarounds that aren't needed anymore and
try to rely more on the existing point cache infrastructure.

Next week I plan to:

* Rework world rebuilding
  (and resetting so we finally can have determinism).
* Hook up point cache and remove properties and old hacks now made
  redundant by it.
* Figure out best way best way to do cache invalidation.
* Add baking for rigid bodies.
* Add point cache ui.
* Improve handling of rigid body types
  (also try to implement kinematic/dynamic switching)
* Fix more collision shape bugs.

No significant problems.