refactored mesh

used stream draw instead of dynamic

updates! ...

moved FXAA
removed gl.id - this is now renderer.CONTEXT_UID
render texture scale mode / resolution now respected

removed shader manager

Added Plane to Mesh class ...

handy for making simple mesh’s
custom shaders now work with mesh shader too

Fix renderer plugin destruction exceptions ...

Closes pixijs/pixi.js#2086.

Merge pull request #2045 from LibertyGlobal/cleanup_fixes ...

Add calls to super destructors and other extra cleanup work.

Revert unneccessary changes from our code base

Add calls to super destructors and other extra cleanup work.

Massive documentation update; fixes many issues. ...

Issues fixed by these documentation updates:

- #1973, fixed filter and BitmapText property docs
- #1908, fixed type reference links
- #1856, fixed name of MeshShader

fix typos

Remove the rest of internal module coupling between packages

minor doc changes

optimize texture property access to bypass the getter

fix rendering problems with mesh and rope

Fix Mesh Rendering to enable pixi-spine Mesh to render properly

fixed extends doc issue

update indices data before drawing

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

Fix all the remaining jshint stuff

Moved the mesh folder to the root