Prop mode goodie;

- Made proportional edit in Mesh editmode use connectivity to clip the
  area where proportional editing is allowed.
  Uses some kind of manhattan distance for clip area still, so is slightly
  too large for diagonals. Will be worked on!

- Fix; in constraint code, using (0 0 0) delta caused NaN.

source/blender/src/transform_constraints.c

@@ -219,7 +219,9 @@ static void axisProjection(TransInfo *t, float axis[3], float in[3], float out[3
 		if(in[0]!=0.0f || in[1]!=0.0f || in[2]!=0.0) {
 			Projf(vec, in, n);
 			factor = Normalise(vec);
-			factor /= Inpf(axis, vec);
+			// prevent NaN for 0.0/0.0
+			if(factor!=0.0f)
+				factor /= Inpf(axis, vec);
 
 			VecMulf(axis, factor);
 			VECCOPY(out, axis);