Introduce module categorization

[edwinRNDR]

As the number of ORX modules is steadily increasing it may be helpful to provide a categorization or tagging system to guide users through the process of finding the modules they want/need.

This categorization would be used in the TOC of the orx repository as well as a potential updated version of the guide

[Treide1]

Just the top of my head I can think of some categories:

• Compatability -> For Hardware (like pen drawer g-code, midi devices, kinect or similar) or Software (like syphon or chataigne)
• Data Structure/ Computation -> kdtree, compute-graph, animation, easing, interval tree
• 3D -> mesh-generator, camera
• GLSL
• Drawing -> color-palette, no-clear

Also a "used in the template" would be nice to see what's used by default like orx-color

[Treide1]

I am wondering how the labeling would be presented to newcomers. I don't see a decent way of doing it with GitHub. Maybe as a separate page in the guide ?