[CM] realloc() for VCTs?

[Bill Schottstaedt]

> But I'd like to do something more complex than vct-map!, and it's likely 
> that I wouldn't know (or it'd be pointless to pre-compute) the exact 
> size of the VCT I would need. 

vct-map! is just a loop using vct-ref and vct-set! to fill the vct --
you can obviously use these yourself to do anything you want with
the vct -- there are lots of examples in examp.fs, etc.  If you
don't know the size in advance, you can do block processing,
or make a big vct and use a part of it, or allocate a new vct
whenever you need to -- the GC is supposed to be your friend.
For vct->channel there's the "dur" argument that sets how much
of the vct is used.