[Soc-2013-dev] Weekly Report #11, 12 Rigid Body Simulation Improvements

[Sergej Reich]

Missed last weeks report, was too overwhelmed to get anything done.
Now things are looking better.

This week I:
* Added collision shape visualization for rigid bodies.
* Fixed issues with collision shape visualization for game engine.
* Redone the activation system (now it's much more simple, wouldn't even
  call it a system).
  Ghost objects are now just a flag instead of being a new rigid body
  type. Having a new type required too many special cases, now the
  implementation is much simpler.
* Improved activation on collision, it's more accurate because we now
  test for actual collisions instead for overlapping bounding boxes.
* Added trigger objects. Rigid bodies can be marked as triggers and used
  for activation.
* Added different activation types. Right now only activation on
  collision with other rigid bodies and collision with only trigger
  objects works.
* Added internal edge info for triangle mesh shapes, makes them more
  stable.
* Added effector weights for individual rigid bodies.


Now that we use more and more of bullet's features, I constantly run
into problems when mixing them.
Especially compound shapes cause problems, need to figure out if those
are bugs or limitations and how to fix them.

Next week I'll work on improving the new features, crossing more small
items from my TODO list and writing documentation.