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

remove isDev; always output sourcemap; add uglify

fix require paths for browserify

initial move to new module folders

tons of jshint and typo fixes

refactor utils

run clena on webgl shaders

clena run on all folders

run clean on strip

run clean on interaction

run clean on utils

run clean on textures

run clena on text

run clean on webgl renderer

cleanup canvas renderers

refactor primitives

refactor loaders

move rewrite TODO to top of readme

refactored geom

refactored the filters

Add checklist of folders to convert

fix some docs

browserify display objects

modify some common exports