The shaderCache is initially created as an object. When the Filter Manager gets destroyed, it should be reset to an empty object, not an array.

* Fix : about filterArea & filterClamp

* Remove needless code

* cosmetice

don't clear the entire target buffer when popping the last filter
  fixes issues with applying multiple filters to a single object

* added check for root

* Added note to future us..

* fixed some filter issues with textures not clearing correctly

* removed commented code

* added a clear to the correct place (when filters are stacked)

* little filter-fix

* removed space

Dev vao state cache

* minimal texture bounds pass 1

* cheeky opts

* tidy up code

* create empty textures

* added empty texture

* couple more tweaks

* fixed empty texture issue

* fixed tweaked so id's sit on glTexture

means it should work on multiple contexts

* tweaked unbound textures

* tidy up

* upped max textures to 4 for mobile!

also sending state to tiling sprite VAO

* removed _activeTetureLocation

* tweaked eslint

* make sure buffer is bound

* updates based on @englercj review points

- Added vertexCount back in as it still yields much faster results in
iOS
- Tidied old comments
- Replaced i++ with ++i

cleanup some export defaults

* added prefer-const rule to .eslintrc

* eslint const autofixes

* manual let to const changes; lint free;

* added brace style 'allman' to eslintrc

* brace style, comment fixes and default arg

* brace style fixes

* more brace styles

* Point default args

* Point brace styles

* Observable Point default args

* more brace styles

* jsdoc comment style

* brace style

* brace styles and small jsdoc fix

* brace styles

* removed unneeded eslint inline comment

* brace styles; lint free

* some more es6 changes
- const instead of let if possible
- arrow functions
- string templates
- argument defaults

* object property shorthand

* some more es6 changes
- const instead of let if possible
- arrow functions
- string templates
- argument defaults

* Revert "Merge branch 'dev-es6-sb' of github.com:stbaer/pixi.js into dev-es6-sb"

This reverts commit 8d3af81, reversing
changes made to e8b9948.

* Revert "Merge branch 'dev-es6' into dev-es6-sb"

This reverts commit 3eeaf79, reversing
changes made to fb69536.

* Revert "Revert "Merge branch 'dev-es6-sb' of github.com:stbaer/pixi.js into dev-es6-sb""

This reverts commit c860228.

* fix RenderTexture, incomplete merge

* fix for text font properties

* reverted some changes

* checked out License, Readme and Contributinf from dev-es6

* editorconfig updated: 2 spaces for .eslintrc

* added eslint rule: spaces around fat arrow

* used eslint fix for consistent spaces around fat arrow

* don't allow scale.x or scale.y to be 0 in displayObject setTransform

* removed jshint comments (again)

# Conflicts:
#	src/core/Shader.js
#	src/core/graphics/Graphics.js
#	src/core/math/shapes/Rectangle.js
#	src/core/renderers/webgl/managers/FilterManager.js
#	src/core/sprites/webgl/generateMultiTextureShader.js