[LilyPond] Output is too verbose

There are lots of comments and blank lines (after \version or music expression in \score) in the exported LilyPond output. Some comments are helpful but there are many which hinder readability. E.g.

%staffkeysig
%bartimesig:
% end of last bar in partorvoice
%% Boosey and Hawkes, and Peters, have barlines spanning all staff-groups in a score,
%% Eulenburg and Philharmonia, like Lilypond, have no barlines between staffgroups.
%% If you want the Eulenburg/Lilypond style, comment out the following line:

Also, double % signs are superfluous.