New Shaders and Demo

[AlexMarinescu]

Implement new shaders for linear and radial gradients, blending between textures and colors as well as better texture filtering.

Redo the tech demo and prototype application; It will use a retro logo as an opening animation for our engine, then it will jump to the two demos: CSG and collision detection. User will be able to switch between the demos via arrow keys.

Regarding applying the shaders like the gradients and blending, I believe this will be a good starting point for the materials class. If anything these are just properties of how the pixels behave on the texture via interpolating and bitwise operations. Thoughts on this?