remove Sprite require from Graphics

fix #1819;comment out old cacheAsBitmap code in Graphics

update some doc comments

properly initialize projectionMatrix; fixes #1811

fix typo in convolution filter

Merge pull request #1792 from drkibitz/chore/move2core ...

Moved ticker to core

Merge pull request #1807 from sweetmandm/dev ...

Fix TilingSprite tilePosition + tileScale bug

Fix TilingSprite tilePosition + tileScale bug ...

Demonstration: http://www.davidsweetman.com/pixi/demo/

When the tilePosition was set to be greater than the texture
width while a tileScale was applied, taking the tilePosition
modulo the texture width would cause the resulting texture
coordinates to drift off of whole steps of the texture.

This fix takes the tileScale into account while applying the
tilePosition.

Merge pull request #1806 from FletcherD/dev ...

cacheAsBitmap should respect .visible property

Merge pull request #1762 from snc/patch-1 ...

Fixed MovieClip when using negative animationSpeed

cacheAsBitmap should respect .visible property

Fix typo in cacheAsBitmap.js

fix issue where refresh could be called too early

don't run mesh ctor until after setting up rope properties

Fix #1800, don't double up the alpha in webgl

optimize texture property access to bypass the getter

fix rendering problems with mesh and rope

minor whitespace updates

fix #1799; vColor should be a vec4 in normalMapFilter

Merge pull request #1784 from simonTadram/dev ...

Fix Mesh Rendering to enable pixi-spine Mesh to render properly

fix #1778; properly size canvas sprite draws w/ resolution

fix #1790; add exports that got removed in 928477c

moved ticker to core

minor jshint fixes

properly handle context restore; fixes #1788

Merge pull request #1772 from GoodBoyDigital/earcut ...

Replace PolyK with Earcut

Fix Mesh Rendering to enable pixi-spine Mesh to render properly

removed old tiling sprite

more doc tweaks

more doc tweaks