fix an exception when tilingsprite is destroyed without being rendered

Fix pixi.js drawOrder. Also, skeleton.drawOrder now is permutation of integers.

Add back in a fix by @photonstorm

Merge branch 'nikeee-master' into v2.x

another fix related to masking tilingsprites on canvas

fix #1378; fix crash in tiling sprite on canvas

fix a typo:

add destroy method to TilingSprite; fixes #1381

Fix #1324, update TilingSprite Texture correctly.

Merge branch 'dev' of https://github.com/GoodBoyDigital/pixi.js into dev ...

Conflicts:
	src/pixi/Pixi.js

Fixed tilingSprite canvas transform bug

-[SPINE] Spine loader uses a canvas padding of 1.5, optimal for most use cases.

-[STRIP] "padding" renamed to "canvasPadding" to reflect the fact that it is only used in canvas mode + canvas padding is calculated using the world transform to make sure it looks right at any scale.

-[SPINE] Fixes Atlas attachment loader bug in which it would try to load the name of the attachment as a sprite instead of the name of the sprite.

-[SPINE] Empty slots are handled properly.

-[SPINE] Fixed nasty infinite loop bug in attachment loader code.

-[HOUSEKEEPING] Fixes JS specific syntax errors.

-[HOUSEKEEPING] Removed extra space.

-[STRIP] Added getBounds function to Strip.

-[HOUSEKEEPING] Removed unnecessary console logs.

-[HOUSEKEEPING] Refactored canvas drawing functions for readability.

-[HOUSEKEEPING] Spelling mistake verticies --> vertices

-[STRIP] Added GL_TRIANGLES drawing mode besides of GL_TRIANGLE_STRIP. Should the name be changed from Strip to Mesh?

-[SPINE] Separates the PIXI.Spine portion into its own file, allows for easier spine.js library updates. Implements new loading system, IK, per bone flip and skinned mesh attachments.

-[SPINE] Spine.js file only contains the spine runtime, modifications needed made it to the official library. https://github.com/EsotericSoftware/spine-runtimes/pull/315

If the BaseTexture dimensions don't match the texture frame then we need a new texture anyway because it's part of a texture atlas

added default blend mode to strip

Fixed blendmode in Srip

swapped b & c in TilingSprite and Graphics getBounds

Fixing issue #1038 ...

Moving anchor point to translate instead of fillRect. Fix for https://github.com/GoodBoyDigital/pixi.js/issues/1038