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_generics.c

@@ -709,7 +709,7 @@ void calculatePropRatio(TransInfo *t)
 			if (td->flag & TD_SELECTED) {
 				td->factor = 1.0f;
 			}
-			else if (td->dist > t->propsize) {
+			else if (td->dist > t->propsize || td->rdist > t->propsize) {
 				/* 
 				   The elements are sorted according to their dist member in the array,
 				   that means we can stop when it finds one element outside of the propsize.
@@ -736,7 +736,7 @@ void calculatePropRatio(TransInfo *t)
 					td->factor = dist;
 					break;
 				case PROP_CONST:
-					td->factor = 1;
+					td->factor = 1.0f;
 					//td->factor = (float)sqrt(2*dist - dist * dist);
 					break;
 				default: