Improved rendering support for rigid-body fluid interaction

Hello everyone,
I have added a lot of new features to the fluid/rigid-body simulator. Here is a bulleted list:

• Added mesh importing support via AssImp Library.
• Fixed lots of bugs in mesh voxelization. Now you should be able to voxelize any arbitrary closed mesh.
• Added parameter files so you can change many system parameters without the need to recompile.
• Improved rendering of rigid-bodies.
• I implemented some basic instance rendering. I plan to reintroduce flocking simulations implemented by Myrna Merced. Then I can take advantage of intanced mesh rendering to render birds, fish etc.
• I have added configurable point source gravity for interesting effects.

I have completed many of the desired features for the stand-alone library. I now plan to dedicate much of my time to integrating the library into Bullet physics engine. Hopefully I can get most of the work integrated within a month. Then I will work on upgrading blenders Bullet interface to include all these new features. In parallel to those two task I would like to also improve the fluid surface extraction.