Rhythmic clusters (i.e. *not* \makeClusters)

[James Harkins]

That other question...

I would like to notate some clusters, but articulated: blocks instead of notes, 
but showing repeated, re-articulated blocks.

\makeClusters doesn't do it. Even if I put a "s"kip in between, it still 
connects them into one massive gesture. Plus, I need rhythmic notation.

Temporarily, I'll use \improvisationOn, but I think that's not right. The idea 
in my mind is to replace the note column with a filled rectangle.

Thanks,
James