Documentation overhaul

[Willy Tschager]

When it comes to primitives, I wish there was some way of automatically creating the primitive reference since the current listing is inaccurate. I often find more primitives in the /p folder than in the reference list. The primitive reference could also be expanded to useful subparts, many of which are known only to particular authors and reviewers.

The updated prim ref should actually be exhaustive: https://wiki.ldraw.org/wiki/Primitives_Reference

Feel free to list what is missing.

w.