fixes wire highlighting in instructions

sim/microbit.ts

@@ -127,6 +127,11 @@ namespace pxsim.visuals {
         {
             visibility: hidden;
         }
+        .sim-wireframe .sim-label
+        {
+            stroke: none;
+            fill: #777;
+        }
         .sim-wireframe .sim-board {
             stroke-width: 2px;
         }

sim/visuals/boardhost.ts

@@ -93,18 +93,15 @@ namespace pxsim.visuals {
         }
 
         public highlightWire(wire: Wire) {
+            //TODO: move to wiring.ts
             //underboard wires
             wire.wires.forEach(e => {
+                svg.addClass(e, "highlight");
                 (<any>e).style["visibility"] = "visible";
             });
 
             //un greyed out
-            [wire.end1, wire.end2].forEach(e => {
-                svg.addClass(e, "highlight");
-            });
-            wire.wires.forEach(e => {
-                svg.addClass(e, "highlight");
-            });
+            svg.addClass(wire.endG, "highlight");
         }
 
         public getView(): SVGElement {

sim/visuals/wiring.ts

@@ -24,7 +24,7 @@ namespace pxsim.visuals {
             stroke-dasharray: ${PIN_DIST / 10.0},${PIN_DIST / 1.5};
             /*stroke-opacity: 0.4;*/
         }
-        .grayed .sim-bb-wire-end:not(.highlight) {
+        .grayed .sim-bb-wire-ends-g:not(.highlight) .sim-bb-wire-end {
             stroke: #777;
             fill: #777;
         }