[A6] Tracking generator

[Tom Moravansky]

> But I think Brian is right about the Tracking Generator ... 
> I still haven't found a use for it, personally ...
> 

In the early beta test days before the sequencer and arpeggiator
were working, it was neat to use the tracking generator to get a
mini-sequence going with every keypress.  Took some fiddling with
levels and amount of pitch mod, but you could get a repeatable 
sequence that way.

Another way I use it is to get a pseudo random sequence of values
as a mod source.  Sometimes I like the sound of S&H modulation,
but sometimes it's nice to be able to predict what it's going to
do.  Use the TG to create your pattern, and then use it like the
S&H generator, so in context it sounds somewhat random, but
within your defined bounds.