* Water grid simulation w/ ShaderMaterial cloned from MeshPhongMaterial

* Water shader works with texture heightmap

* Added GPUComputationRenderer, I'm about to test it

* GPUComputationRenderer works with water simulation

* Interaction with mouse

* Added water viscosity, simple geometry for mouse picking

* Put pass thru shaders in GPUComputationRenderer. Some minor refactoring.

* Code revisison, added comments and explanations. Inverted mouse Y coord.

* Added GUI controls for some water parameters.

* Commencing conversion of birds gpu demo to GPUComputationRenderer

* Converted gpu birds demo to GPUComputationRenderer and fixed bugs in it.

* Solved mouse bug.

* Optimized smoothWater(), renamed some GPUComputationRenderer methods.

* Substituted old bird gpu implementation. Preparing for new demo.

* Removing old SimulationRenderer

* GPU protoplanets demo started. Minor tweaks in the other demos

* Starting to implement the particle demo

* $th component of texture now is usable. It was the GPUComputationRenderer
pass-through fragment shader.
Next thing to do is use a texture that contains (vx, vy, vz, mass).

* Particles already move. Next is gravity interaction.

* Gravity interaction done. Next is particle collision and aggregation.

* Particle collision works

* Added gui

* Some minor adjustments

* Added the two new demos to the list of examples