rings.icn: Program to draw tiles of rings and circles

This program produces seamless tiles with drawings of circles and
rings.

It words from characters input to the window:

     q       quit
     c       draw 10 random circles
     r       draw 5 random rings
     W       writes image to GIF file; files are named ring000.gif,
                ring001.gif, ...
     E       erases the window
     F       fills the window
     R       reverses the colors

At present there are no options except those provided for
opening the window.

Some modifications have been made by Ralph E. Griswold