[CM] locsig with stereo sound

[Bill Schottstaedt]

 > What I would do is split the stereo soundfile into two different mono
 > soundfiles and then  locsig (or dlocsig) each soundfile separately. You
 > will have two stereo soundfiles which can be further mixed into one
 > stereo soundfile.

You can have two or more locsigs running, so you could also do the
separation/remix in the run loop (rather than writing mono files out).