Move glyphlist and lilyglyphs-logo dirs below documentation

in order to make the directory structure more organized
Manual: Move font selection to dedicated package

Remove dependency of lilyglyphsStyle.sty from our font selection.
The files generated by the Python scripts \use lilyglyphsStyle, so they shouldn't
use non-standard files because that would raise errors on most
users' computers.
Add lilyglyphs_private structure

A place where users can put new commands without touching the original package files.
Document this in 'private directory structre'

TODO: Before release this has to be archived to lilyglyphs_private/lilyglyphsPrivate.tar.gz
Manual: several small touches