Merge pull request #7 from unicomp21/master

fixing a couple issues flagged by dart editor 1.4.2
added cameraNear, cameraFar and (canvas) size uniforms
added a SSAO postfx shader
added a SSAO example
added helpful docs to the vector cross and dot functions.
added createPlane2ColorShader to improve edge detection.
According to the Dart style guide it is not good to create classes just to wrap static methods like I did in ShaderLib.
And since I am adding shaders all the time it was not feasible anymore anyways.
So I moved all createShader function to the top level. ( this is a breaking change, sorry! )
I also added an edge detecting sobel shader and matching example.
added an example index.html file
added a Perlin noise shader