Feature/filters (#4687) ...

* Done
- filters working
- nested filters working
- Less GPU calls than v4
- Now passing destination and source frames to shader to calculate verbs
- ONLY Color Matrix Filter working
- Filter Area is now transformed (like hit area, much more useful!)
- Less code :D

Todo
- Apply Filter no complete
- Multiple filters not. Complete
- Refactor other filters

Optimisations
- need to pool the FilterStates

* Smarter check to eliminate needles enabling of stencil

* - Quad draws with triangle strip
- multiple filters now working

* Fixed up resolution

Not only does resolution now work - but any texture pass can be ANY
resolution and it works like a champ!

* Moved docs removed a needless comment

* More optimisations

- Added caching layer to viewport
- renamed getRenderTarget -> getFilterTexture
- added active state to filter for easy access
- fixed and optimised blur filter at least 66% less gpu calls required
now :)

* Fix up alpha filter

* Fixed up all bundled filters!

* Filter clamp added to Displacement filter

* Fixed lint fail

* Fixed up use of ba instead of zw in shader

Also added defaultFilter vert

* Added doc to state in filter

* space..

* Added pooling and a few docs bits

* more tweaks

fixed blur Y filter bug
Fixed default filter frag bug
Set default padding to 0

* Removed the slice from filters #3639

* Added auto fit back in

We now Loop through filters to find appropriate padding / autoFit /
resolution rather than just checking first filter.

Also clamped blur in vertex shader so that it does not bleed
transparency around its edges

* Update eslint package

this seemed to fix it last time..

Removes "$>" chars from command-line README snippets (#4681)

Expose earcut dependency in PIXI.utils (#4676)

Fix comment mistake for Matrix (#4655)

Fixed issue where uTransform was not being set causing uvs to be calculated incorrectly (#4652) ...

* Fixed issue where uTransform was not being set causing uvs to be calculated incorrectly

* oops.. used PIXI instead of importing

Improve setChildIndex error message (#4644)

Update the mouse position in onPointerMove when using a pen tablet (#4622)

Better support for various Spritesheet trimmed formats (#4490)

Follow W3 specs for `pointerId` mouse value (#4606) ...

See: https://www.w3.org/Submission/pointer-events/#widl-PointerEvent-pointerId

Fixes disabling interactive children outside of hitArea (#4608)

Adds `drawStar` method to Graphics (#4612)

Graphics class has a property called "isMask" which is never actually set (#4609)

[next] Particles fix (#4600)

Support blendModes with NineSlicePlane and CanvasRenderer (#4603)

Fixes handling of sprite sheet error (#4601)

[next] Fixes Mesh canvasPadding default setting (#4549) (#4592)

Fixes Garbage Collector system (#4593)

[next] Math `copy` inconsistencies (#4595) ...

* copy-from and copy-to inconsistency

* faster copyFrom for ObservablePoint

* deprecations

* Fixes deprecations docs

Fixes CanvasRenderer (#4588)

Windows tests are failing (#4589)

Update LICENSE files to 2018 (#4585)

Destroy generated textures in extract (#4562)

README Link Updates (#4574)

fixed jsdoc annotations (#4577) ...

* fixed jsdoc annotations

* Converts function tag to method tag

Adds pre-commit dependency and hook (#4580)

Fix DisplacementFilter when using multiple filters (#4560)

Fixes indentation lint issue

Removes default loadType from the spritesheetParser load options (#4573)

Bugfix/frame buffer textures (#4578) ...

* Fixes issue with frame buffers if depthTexture or colour texture are auto generated

Easy fix, we forgot to update the texture constructors to use the new
resource / object format.

* Lint fix, oops

Fixing mipmaps and renderTexture (#4559)