comments and jsdoc

+ GroupD8 math module ...

+ texture rotations
+ fix bug in Sprite that causes changes in worldTransform every render

fixes jshint errors

added skew property to DisplayObject

Massive documentation update; fixes many issues. ...

Issues fixed by these documentation updates:

- #1973, fixed filter and BitmapText property docs
- #1908, fixed type reference links
- #1856, fixed name of MeshShader

Depecrate `PIXI.math` namespace ...

Access math members from PIXI when outside of core, require the math module directly when inside of core.

add out param to Matrix#toArray

Move items into their namespace ...

This commit also:

 - fixes some dangling whitespace,
 - fixes some incorrect docs in extras/mesh,
 - moves Text to core
 - moves BitmapText to extras
 - moves math constants to const.js

fix some typos and jshint issues

fix a couple minor argument deopts

`copy` and `equals` methods for the Point object

docs oversight, sorry

Tidying up some stuff

remove some @method tags, was confusing jsdocs

massive jsdoc fixes

fix jsdoc errors

docs, more on graphics, plus particles and textures

Docs, mostly the display and graphics folders and some filetype update

Caches x and y from point so that the calculation is correct even when pos and newPos is the same PIXI.Point.

Caches x and y from point so that the calculation is correct even when pos and newPos is the same PIXI.Point.

fix #1384

moar jshint fixes

big changes ...

all still a little in flux!
sprite masks added..

misc jshint fixes

added matrix to shaders

regex replace braces to newline

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

initial move to new module folders