PATHC: (0.55) bug fix (dimension_is_essential)

[Mark-Jason Dominus <mjd@xxxxxxxxxx>]

In 0.55, `dimension_is_essential' would have incorrectly reported that
the dimension `d.d.marky-mark' was essential.  This is a fix.

I wonder if it's appropriate to make d.3 essential.   But this is a
policy matter and Not My Problem.


--- zigzag.orig	Tue Oct 27 22:55:17 1998
+++ zigzag	Fri Oct 30 17:03:50 1998
@@ -440,7 +440,7 @@
 sub dimension_is_essential($)
 {
   my $dim = shift;
-  return ($dim =~ m/.?d\.(cursor|clone|1|2|3|inside|contents|mark)/);
+  return ($dim =~ m/^[+-]?d\.(cursor|clone|1|2|3|inside|contents|mark)$/);
 }
 
 sub dimension_exists($)