rstarlab.icn: Program to draw regular stars

This program draws regular stars.  See

     Geometric and Artistic Graphics; Design Generation with
     Microcomputers, Jean-Paul Delahaye, Macmillan, 1987, pp. 5-7.

The window is square.  The window size can be given on the command line,
default 600.

The present user interface is crude.  To see all the regular stars
that are provided by default, type

     all

from standard input.  After each star is drawn, the program waits
for an event before going on to the next star.

Alternatively, a single star can be drawn by typing its name preceded
by an equals sign.  The names are rstar01 through rstar06.  For example,

     =rstar02

draws the second star.

In future extensions, provision will be made for user-defined stars.