* Migration to ES6 classes

* Migration to ES6 classes

* Migration to ES6 classes

* Migration to ES6 classes

* Using babelify to transpile ES6 code

* Adding babel-preset-es2015 in devDependencies

fixes #2841

* some stuff in renderer

* unused variable

* sprite bounds tweaks

* added a trimmed sprite test

* tweaks to tint

wrong place i know..

* Precision errors can be very strange on some devices. Especially if you are rendering 3d transform. This is part of gameofbombs/pixi.js fork, I didnt think that it will be needed in 2D scenes too.

* looks better

This fixes an android issue where texture id attribute is not defined.

Conflicts:
	src/core/text/Text.js

# Conflicts:
#	src/core/renderers/webgl/WebGLRenderer.js
#	src/core/sprites/webgl/SpriteRenderer.js
#	src/extract/canvas/CanvasExtract.js
#	src/extract/webgl/WebGLExtract.js

optional gl context for if statement checker (this way does not block
the gl inspector)
added Filter deprication

# Conflicts:
#	src/core/sprites/webgl/SpriteRenderer.js

It was possible for a group of sprites to all have a blend mode != 0, never reaching currentGroup.blend = blendMode, resulting in the group rendering with the default blend = 0;