continuously varying Julia set
Sean McCullough

History 01-Nov-2000: Allocation checks
28-May-1997: jwz_at_jwz.org: added interactive frobbing with the mouse.
10-May-1997: jwz_at_jwz.org: turned into a standalone program.
02-Dec-1995: snagged boilerplate from hop.c
used ifs {w0 = sqrt(x-c), w1 = -sqrt(x-c)} with random
iteration to plot the julia set, and sinusoidially varied
parameter for set and plotted parameter with a circle.