complete lilyglyphs-example
Make font selection lua/xetex aware

Emmentaler fonts have to be in the texmf tree
(will be there when installed in a distro).

Xetex can find opentype fonts only by file name,
Luatex only by font name (arrrgh).

This commit lets both texes find it.

BUT: When a font is installed system-wide xetex only finds it
by font name (arrrrgh arrrrgh).

Therefore we have to tell the user to install the font in texmf.
scripts: Add argument functionality (base)

Using argparse it is easy to implement the (required)
--help and --version arguments

Additionally there is an unnamed (INPUT) argument
that requires the name of an existing file
(relative to CWD or absolute)
example doc: Clean up

move \superscript definition to preamble
use lilyglyphs default fonts again
example doc: fundamental review

Make this document much more of an advertisment than before.
'Whet the appetite' from a use case POV,
stress advantages and only at the end reveal that you
have to change your mind and use plain text :-/