New port: audio/guidolib: Library for graphic rendering of music scores

Guidolib implements a new way to encode and typeset music on computer.
The common, most ubuiquitous way is MusicXML. It is the XML schema that is hardly
readable for humans. Guidolib takes an alternative approach, and represents
music notation in a way very similar to a computer program. It is easily
readable and writable by humans.

http://guidolib.sourceforge.net/

PR: 221838
Approved by: tcberner (mentor)
Differential Revision: D13705