Add some docs for source

remove need for global webglRenderers array

Add dispose method

fix some jshint issues

merge #1186, implement fixes for video texture in FF

Fix typo in fromImage logic ...

This bug was introduced in 1a96f90

merge #1176, fix regression in RenderTexture

merge #1193, fixes for Base Texture loading code

make texture frame a setter; clear up some typos

minor style tweaks

reorg webgl utils; move primitives to core; refactor shape types

successful removal of globals and _dirty flags

Lots of core renderer-related updates ...

- Removed `Stage` completely from core lib, in favor of directly rendering
  DisplayObjects
- Removed rendersession from core lib
- Rewrote WebGL managers to be more DRY and have a common base
- Rewrote Shaders to be more DRY and have a common base

fix require paths for browserify

initial move to new module folders