GDP: consistency in @q @qq @samp @code

[Graham Percival]

I'd like to have some consistent usage amongst these terms.  Here's my 
proposal:

@code{}: actual lilypond code or property/context names.

@qq{}: only for actual quotes -- ie "he said" or "she wrote".

@samp{}: refers to pieces of notation, such as: @samp{crescendo} is 
often abbreviated as @samp{cresc.}.

@q{}: used for `vague' terms in English (and other natural languages).


Does this make sense?  If we agree on these, I'll add them to the doc 
policy.

Cheers,
- Graham