Docs
* Update and streamline readme.md
* Add quicksheet for overall
* More crosslinking
Infra
* Add markdown support to docsite
* ReadTheDocs homepage reuses github README.md
* Docs pip install caches
* Drop SVGs and external images during latexpdf generation
Changed
* Treemap import `squarify` deferred to use to allow core import without squarify installed, such as in `--no-deps`