* Fix the exception if an unused uniform is defined.

* Use property accessor for checking uniform  instead of `hasOwnProperty.call`

* filters can survive context loss

* falsifying.

* Fixed nested stencil masks not rendering correctly.

* Fixed jslint errors.

* Documented the changes.

https://github.com/pixijs/pixi.js/issues/2559
https://github.com/pixijs/pixi.js/issues/2877

* Standardizes how pixi is represented as a name, adds missing meta jsdoc fields

* Replaces more missing instances

* Missing package.json description

* Fixes contributing with brand

* Cleanup the repository mentions in contributing doc

* autoFit temporary fix

* one line

* Fix `the fault after merge`

* Remove duplicate comment

* Update Filter.js

* Update Filter.js

* Pass ```currentState``` to filter.apply()

see https://github.com/pixijs/pixi.js/issues/3317 

If  pass ```currentState``` to filter.apply() , users could get more informations  (e.g. get current sprite by ```currentSprite = currentState.target```).
It's very useful when users create custom filters.

And the ```currentState``` is the last argument , and pass it won't break any filter already existed.

So I think this PR is safe and useful.

* Update annotation about currentState in Filter.js

* Use eslint-disable-line

* Update FilterManager.js

* Update Filter.js

* Revert "Fix #3609 , about `filterClamp` & `filterArea`  (#3626)"

The real fix is to exclude "filterClamp" from uniformData
That fixes outlineFilter and glowFilter

* added a test, so finscn wont break it again ;)

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