Add a linkcatcher widget

It intercepts navigation events and saves the target tiddler title into
a specified text reference

core/modules/widgets/linkcatcher.js

@@ -0,0 +1,56 @@
+/*\
+title: $:/core/modules/widget/linkcatcher.js
+type: application/javascript
+module-type: widget
+
+Implements the linkcatcher widget.
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var LinkCatcherWidget = function(renderer) {
+	// Save state
+	this.renderer = renderer;
+	// Generate child nodes
+	this.generate();
+};
+
+LinkCatcherWidget.prototype.generate = function() {
+	// Get our attributes
+	this.to = this.renderer.getAttribute("to");
+	// Set the element
+	this.tag = "div";
+	this.attributes = {
+		"class": "tw-linkcatcher"
+	};
+	this.children = this.renderer.renderTree.createRenderers(this.renderer.renderContext,this.renderer.parseTreeNode.children);
+	this.events = [
+		{name: "tw-navigate", handlerObject: this, handlerMethod: "handleNavigateEvent"}
+	];
+};
+
+LinkCatcherWidget.prototype.refreshInDom = function(changedAttributes,changedTiddlers) {
+	// We don't need to refresh ourselves, so just refresh any child nodes
+	$tw.utils.each(this.children,function(node) {
+		if(node.refreshInDom) {
+			node.refreshInDom(changedTiddlers);
+		}
+	});
+};
+
+// Navigate to a specified tiddler
+LinkCatcherWidget.prototype.handleNavigateEvent = function(event) {
+	if(this.to) {
+		this.renderer.renderTree.wiki.setTextReference(this.to,event.navigateTo,this.renderer.getContextTiddlerTitle());
+	}
+	event.stopPropagation();
+	return false;
+};
+
+exports.linkcatcher = LinkCatcherWidget;
+
+})();