Version 1200 was commited by markb on 2009-09-17 12:13:18 +0100 (Thu, 17 Sep 2009) Tweaked diagnostic messages. Now distinguishes between zero length arcs and short arcs when reporting the fact that it really would like to merge two nodes but it can't because they are both boundary nodes. The zero length arc occurs if the two nodes have the same coordinates, the short arc occurs if the two nodes are closer than some threshold distance.