GUI -- TopoView - implemented show/hide background map ('B' keystroke)
- reworked SvgUtilService.makeVisible() to be dual-purpose .visible(el, [b]) method.

Change-Id: I8e68994627d1022066cdc9dcbed006675431d91a
diff --git a/web/gui/src/main/webapp/app/view/topo/topo.js b/web/gui/src/main/webapp/app/view/topo/topo.js
index c413347..00b06d5 100644
--- a/web/gui/src/main/webapp/app/view/topo/topo.js
+++ b/web/gui/src/main/webapp/app/view/topo/topo.js
@@ -48,7 +48,7 @@
 
             H: [tfs.toggleHosts, 'Toggle host visibility'],
             M: [tfs.toggleOffline, 'Toggle offline visibility'],
-            //B: [toggleBg, 'Toggle background image'],
+            B: [toggleMap, 'Toggle background map'],
             //P: togglePorts,
 
             //X: [toggleNodeLock, 'Lock / unlock node positions'],
@@ -94,6 +94,10 @@
         tfs.updateDeviceColors();
     }
 
+    function toggleMap() {
+        sus.visible(mapG, !sus.visible(mapG));
+    }
+
     function resetZoom() {
         zoomer.reset();
     }
@@ -184,7 +188,7 @@
     }
 
     function showNoDevs(b) {
-        sus.makeVisible(noDevsLayer, b);
+        sus.visible(noDevsLayer, b);
     }
 
     function showCallibrationPoints() {