add removeView to webgl destroy; default it to false in both renderers

fix #984, null errehthing on webgl renderer destroy

Add dispose method

update colorAttribute to be aColor

fix some require paths that changed with some refactoring

fix some jshint issues

rename shader classes

merge #1313, fix multi-path masks in canvas

merge #1186, implement fixes for video texture in FF

move primitives back into core

Fix typo in fromImage logic ...

This bug was introduced in 1a96f90

merge #1192, allow filters to go 'offscreen'

minor tweaks to shader attrs

merge #1052, fix EJECTA issue where renderbuffer isn't reset

merge #1113, reuse code in autoDetectRecommendedRenderer

merge #1171, use gl.isContextLost()

merge #1176, fix regression in RenderTexture

merge #1193, fixes for Base Texture loading code

merge #1216, small getBounds optimization

merge #1310, log type when not chrome

update extras to new renderer methods

make texture frame a setter; clear up some typos

move all render webgl code to DOC

minor event target speed boost

minor style tweaks

move cacheAsBitmap to DOC

move primitives back into a separate module

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