<_description>
Repeatedly draws random Celtic cross-stitch patterns.
-http://en.wikipedia.org/wiki/Celtic_knot
-http://en.wikipedia.org/wiki/Knots_and_graphs
+https://en.wikipedia.org/wiki/Celtic_knot
+https://en.wikipedia.org/wiki/Knots_and_graphs
Written by Max Froumentin; 2005.
</_description>