maxx = 128.
maxy = 95.
bxl	(n,p) pat (x0,y0,w,ht, hor,ver,col,rows) q (xlit)

	pat=pattern name or reciprocal probability
	    if pat is an integer, this is done with probability 1/int.
	    x0,y0 are center points of box
	    w = width of box
	    ht = height of box
	    hor = horizontal spacing between boxex
	    ver = vertical     "       "       "
	    col = number of columns done
	    rows=   "    "  rows     "
	    q   =

	    xlit= transliteration string

chv	(n,p)param,change,val1,val2[,goto]
	    param = variable to be changed
	    change= 'set','add','sub','mpy','div'
		val1	= lowest value for range
		val2	= highest value for range
			  random choice is made among values between
			  val1 and val2 inclusive.   if val2=val1
			  or if val2  is omitted,  val1 is used exactly

	xlit strings: values are:  0,1,2,...,9,a,b,c,...,w,x,y,z
	for hex nets, neighbors are newsrl only
	neighbors are a=above
		b = below
		r = right
		l = left
		n = north
		e = east
		w = west
		s = south

	list is a truncated list. positions not specified => characters
	 remain unchanged.
	there is a '...' option in  the original version.
		xza34... => last character  specifed fills out remainder
		of list.
		perhaps the '.' indicates front or back fill in this
		version.

most commands are of the form:

tag	command		args [,optional goto label]
	the character 'x' can be special, and indicates 'except':
	(n,p) = (x,1,x,3) means
	wbt	white,black,twinkle
		the points whose values are in the twinkle set are on
			at random 50% of the time.
	(n,p)	every n-th time, perform with probability 1/p.

commands:
axl
baxl
caxl
cxl
camera
chv
do
goto
if
mode
wbt
xl
xli

mode:	wrp,pln,run,tst
wbt:	white codes get a bright dot in tek version
	black codes are off
xl	transliteration
axl	adjacency condition transliteration (locop)
bxl	box array of transliteration
do	do subroutine and return
chv	change value

periodic and probabilistic
	x = except for
	(x,60,1) except for every 60th, do it
	(1,x,9) do it every time with
	probability 1/9
	(x,2,x,50) do it almost always (probability 1 - (1/50)) on odd
		numbered passes
	most commands can optionally terminate in a goto label.
	q is the probability spot-by-spot
axl:	(n,p) number-of-neighbors,directions,change-string,q,(xlit)[,goto]
mode	hx,sq
	all but the first time, and with probability 1-(1/3)
