Merge pull request #1925 from mreinstein/dev ...

update stale DisplayContainer docs. Remove broken normal filter.

Add callback for when children change; #1988 ...

This is a rebase of the commits in #1988 to squash it down to a single
commit and remove the extra merge commits in @bchevalier's repo.

update docs to reflect sprite support in v3 #1639

send Container as reference on added/removed events. #1870

trigger 'added' and 'removed' events for Container children.

manual merge of #1826; fix generate texture scaleMode

fix small doc comment

more doc tweaks

more doc tweaks

fixed extends doc issue

fixed generate texture parameter issue

remove some private docs

update for new event emitter api

minor cleanup of destroy methods

fixed cachAsBitmap issue

Move items into their namespace ...

This commit also:

 - fixes some dangling whitespace,
 - fixes some incorrect docs in extras/mesh,
 - moves Text to core
 - moves BitmapText to extras
 - moves math constants to const.js

fixed getBounds on Sprite ...

sprite getBounds now takes sprites children into account

rework v3 to use EE3 instead of a custom emitter

Fix all the remaining jshint stuff

Fix recursive destroy children

Tidying up some stuff

Added destroy methods and fixed sprite bug #1505

Strip and rope docs, and usage examples

Put most rendering code in _renderCanvas to match _renderWebGL

Docs docs docs

massive jsdoc fixes

Docs, mostly the display and graphics folders and some filetype update

Fixed up cacheAsBitmap ...

Now works nicely with filters.

cached getBounds each frame ...

handy for all sorts of things!
removed ‘isMask’ as ‘renderable’ provides a more flexible approach

normalize constants to all be caps