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

fixed extends doc issue

Reference issue for all fs requires (fixes typo as well)

Move require('fs') out of the constructor to the top.

massive jsdoc fixes

Fix requires and readFiles in filters

refactor filters to have separate files for shaders