[Groff] groff_lilypond version v0.3

[Bernd Warken]

A new request was added for including lilypond files into a groff file.
.lilypond include ...

There can be several file names in the argument, possibly encircles
by single or double quotes.

This request can be inside or outside of a lilypond range in the groff
file.

Now several groff files can be given in the command line, including `-'
and `--'.

Bernd Warken