requestAnimFrame in WebGlUtils becomes requestAnimationFrame, and, in addition, avoid polluting window's own properties so that we can test the number of global objects in tests/no_globals.html.

hide underscore.js invocation under a special this object so it does not poop on the global namespace.

Add requirejs amd support for Lux. In case lux detects requirejs, it does not pollute global namespace at all, instead returns all objects inside Lux: Lux.Shade, Lux.LinAlg.vec, etc.

Closes #3.
explicitly include underscore in demos now that lux doesn't leak it