GDP: fifth arrangement

[Graham Percival]

http://lilypondwiki.tuxfamily.org/index.php?title=Doc

General notes:
- we're only dealing with the Notation Reference now.  I want to get 
this finalized so we can start the real work, so things like Titles / 
page formatting / changing defaults / etc   will be dealt with later.

- stuff from the old instrument-notation will be dealt with as we come 
to them in GDP

- The most important... the only important... stuff right now is to have 
material in the right sections, and ideally have stuff in the right 
subsections for the non-instrument notations.

Cheers,
- Graham