[CM] Chaining effects together

[Bill Schottstaedt]

It's a bit strange in CLM to write *reverb* as a temp file; to fix
the problem you mention, you could pass the input and output temp
file names to the various instruments (there's nothing special
about *output* and *reverb* besides being built-in), then use
open-output and open-input to get the ina/outa "stream" pointers.

In CLM, the expectation is that each instrument is mixing its
output, so

> 	    (mix (with-sound (:reverb unity :revfile "plain.rev" :output "plain")
>			     (good-saw 0 1 200 0.3)))

is more "naturally" done as:

	(good-saw 0 1 220 .3)

or perhaps via with-mix or sound-let.

> ;; Unity is probably not the best name, but I can't remember the name I really want.

identity? or copy?