Fix bug #217 Reversion of one point guides.

runtime.in

@@ -977,7 +977,7 @@ guide *reverse(guide *g)
   guidevector v;
   size_t start=cyclic ? n : n-1;
   knot curr=f.Nodes(start);
-  knot next;
+  knot next=curr;
   for(size_t i=start; i > 0; --i) {
     next=f.Nodes(i-1);
     v.push_back(new pairguide(curr.z));