This routine determines the pattern of vectors and arcs generated by
future calls to the LX color graphics routines LXVEC and LXCVEC.
PATTRN is a 16-bit integer which specifies the pattern. The high
order 4 bits define the length of the pattern (0 for a solid line).
The low order 12 bits describe the pattern, with the high order bit
being used first. PATSIZ is a 16-bit integer which defines the
number of replications of each bit in the pattern. Pixels associated
with a pattern bit value of 1 are displayed normally. Pixels
associated with a pattern bit value of 0 are skipped completely. They
are neither set nor cleared. After a call to LXRST the pattern will be
set to a solid line.