Improved interaction between rigidbodies and fluid

I fixed a lot of bugs in my simulation framework. Here is a video showing my progress.



Bugs:

• I wasn't properly scaling the positions for the rigidbody simulation to match the fluid simulation.
• Some of my quaternion calculations were not correct when updating the rotation of the rigid body.
• The coefficients for the interaction forces weren't calculated correctly.  I found a detailed formulation for the dampening coefficient in [1].

Features:

• I refactored the rendering code so you can switch rendering techniques on the fly.
• The test program has run-time configurable mass and dimensions for rigid bodies being added.
• Velocity visualization can be turned on/off during run-time.

My plans now are to push my changes into the blender version that Ian already created. Once I have done that I will create some examples and work on writing up my Master's thesis. From then, I will return to working on integrating the library into Bullet. Hopefully, I will get a chance to work on some visualization as well.

[1] Cleary, P. W., & Prakash, M. (2004). Discrete-element modelling and smoothed particle hydrodynamics: potential in the environmental sciences. hilosophical Transactions of the Royal Society - Series A: Mathematical, Physical and Engineering Sciences, 362(1822), 2003-2030. The Royal Society. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/15306427