add bool uniform support in the shader

Expose drawModes like blendModes ...

This separates the pixi contant value from the GL constant value. Even
though right now they *should* be the same, if there are platform
differences, or changes in the future ours will always work this way.

properly initialize projectionMatrix; fixes #1811

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

minor jshint fixes

properly handle context restore; fixes #1788

doc tweaks

more doc clean ups..

fixed extends doc issue

stub destroy method for canvas mask manager, fixes #1744

fix webgl manager destroy to remove correct event handler

5x5 to 5x4, fixed some wording and general cleanup

remove some private docs

fixed initial filter texture upload bug

fix #1727 move viewport resize

resize gl viewport in webgl; fixes #1712

update for new event emitter api

reset drawCount each render call; fixes #1661

fixed a bug i introduced ...

because I’m a donut..

Fixed filter area clone bug

fixed filter issue

fixed filterArea bug

Fixed issue with hardcoded max Attributes

find webGL resize issue

Fixed some dodgey updates that made it in.. ...

Not sure how that got uploaded, sorry bout that!

webGL tweaks

set default render target when created

fix bug where rendertarget isn't set right

restore default blendMode when drawing filter

fixes #1547 - negative viewport values for off screen