Corrected the plow width rules. However, plow spacing rules seem

to be not quite right, and all sets of rules need to be updated
to match the latest DRC rule parsing.  Also, plowing does not
handle contact types correctly.

plow/PlowTech.c

@@ -227,7 +227,7 @@ plowWidthRule(argc, argv)
 {
     char *layers = argv[1];
     int distance = atoi(argv[2]);
-    TileTypeBitMask set, setC, tmp1;
+    TileTypeBitMask set, setC;
     PlaneMask ptest, pmask;
     register PlowRule *pr;
     register TileType i, j;
@@ -244,7 +244,6 @@ plowWidthRule(argc, argv)
 	return 0;
     pNum = LowestMaskBit(pmask);
 
-    set = tmp1;
     TTMaskCom2(&setC, &set);
     TTMaskAndMask(&setC, &DBPlaneTypes[pNum]);
 
@@ -335,8 +334,8 @@ plowSpacingRule(argc, argv)
 	 * Must not have 'set2' for 'distance' to the right of an edge between
 	 * 'set1' and the types in neither 'set1' nor 'set2' (ie, 'setR').
 	 */
-	set1 = tmp1;
-	set2 = tmp2;
+	tmp1 = set1;
+	tmp2 = set2;
 	planes1 = planes2 = PlaneNumToMaskBit(pNum);
 	TTMaskCom(&tmp1);
 	TTMaskCom(&tmp2);