Extending AR integration with categories tools

Includes:
* Categories tools
* NumpyGlyphs speed enhancements
* Balanced zoom in zoom-fit
* Overlay-plot support (using 'hold', but only one can have a server datasource)
* Extended spread to do anti-aliasing (off by default, use with care)

enormous `return`, jeje... can you assign this checks to variables and return those ones... or rewrite this in something more readable? thanks!