Shorthand for \repeat unfold for individual notes

[Aaron Hill]

There is already shorthand for tremolo repeats, so I wondered if there 
could be the same for cases when a single note or rest is repeated.

%%
% Start with music that has repeated notes:
{ \time 7/8 a8 8 8 b16 16 16 16 c4 }

% Manually unfolded repeats work, but take up a lot of input space:
{ \time 7/8 \repeat unfold 3 a8 \repeat unfold 4 b16 c4 }

% This produces the correct length of music without note repetition:
{ \time 7/8 a8*3 b16*4 c4 }

% Possible shorthand for unfolded repeat:
{ \time 7/8 a8**3 b16**4 c4 }
%%

In a sense, the ** acts like (integral) scaling of a duration but with 
unfolded repetition as the realization.


-- Aaron Hill