new new doc

* new technical documentation theme
* technical documentation rewrite (in progress)
* attempted to improve XML data files handling while documenting it
  - rewrote some rng
  - removed remnants of `<wizard>`
  - removed code for `<getitem>` (whatever that used to be)
  - removed icons stuff in `<menuitem>`
* simplified scaffolding command
* reformatted/rewrote a bunch of docstrings

Should probably be folded to a single commit when merged, no point in keeping intermediate crap for this specific branch I think (to check)