track - demonstrates slab3d DSP parameter tracking.
track( smoothtime, nframes, framesz, seed )
smoothtime - slab3d's leaky integrator tracking filter time constant (ms)
nframes - number of DSP frames to display
framesz - DSP processing frame size in samples
seed - if negative, parameter targets are random, seeded with -seed;
if positive, all targets equal seed
Defaults: 15, 128, 32, -1