Folio text overhaul
- general clean up / refactor
- added a jupyter notebook for testing / inspecting visual output: https://scm.medienhaus.udk-berlin.de/daniel/fibel/-/blob/freder-folio-text/Fibel/folio-test.ipynb
- fixed justification bug (line would overshoot horizontal bounds due to kerning)
- use constant line spacing (as opposed to variable, depending on text content)