deletion bug fixed that could orphan a large section of the tree. the
"parent" argument to rotate_left or rotate_right was sometimes not
really the parent of the rotation vertex, because the parent's parent
was not correctly reidentified after a rotation done on the parent.
Minor:
forward static declaration of dns_rbt_printnodename, useful in debugging.
level_matches set correctly for exact match in dns_rbt_findnode (it was
one too few, but this was minor because as yet level_matches is only
used by other code when a partial match was made.
insist 'node' is a child of 'parent' in rotate_left and rotate_right
compare a pointer explicitly to NULL that was just "if (pointer)"
"would would" in a comment changed to just one "would".
401fc772b1