fixed getNodeAt and getEdgeAt functions

lib/network/Network.js

@@ -466,8 +466,20 @@ Network.prototype.stabilize           = function() {return this.physics.stabiliz
 Network.prototype.getSelection        = function() {return this.selectionHandler.getSelection.apply(this.selectionHandler,arguments);};
 Network.prototype.getSelectedNodes    = function() {return this.selectionHandler.getSelectedNodes.apply(this.selectionHandler,arguments);};
 Network.prototype.getSelectedEdges    = function() {return this.selectionHandler.getSelectedEdges.apply(this.selectionHandler,arguments);};
-Network.prototype.getNodeAt           = function() {return this.selectionHandler.getNodeAt.apply(this.selectionHandler,arguments);};
-Network.prototype.getEdgeAt           = function() {return this.selectionHandler.getEdgeAt.apply(this.selectionHandler,arguments);};
+Network.prototype.getNodeAt           = function() {
+  var node = this.selectionHandler.getNodeAt.apply(this.selectionHandler,arguments);
+  if (node !== undefined && node.id !== undefined) {
+    return node.id;
+  }
+  return node;
+};
+Network.prototype.getEdgeAt           = function() {
+    var edge = this.selectionHandler.getEdgeAt.apply(this.selectionHandler,arguments);
+    if (edge !== undefined && edge.id !== undefined) {
+      return edge.id;
+    }
+    return edge;
+  };
 Network.prototype.selectNodes         = function() {return this.selectionHandler.selectNodes.apply(this.selectionHandler,arguments);};
 Network.prototype.selectEdges         = function() {return this.selectionHandler.selectEdges.apply(this.selectionHandler,arguments);};
 Network.prototype.unselectAll         = function() {return this.selectionHandler.unselectAll.apply(this.selectionHandler,arguments);};