Add "info" widget for displaying information about tiddlers

Currently only supports displaying the changecount of a tiddler

core/modules/widgets/info.js

@@ -0,0 +1,50 @@
+/*\
+title: $:/core/modules/widget/info.js
+type: application/javascript
+module-type: widget
+
+Implements the info widget that displays various information about a specified tiddler.
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+var InfoWidget = function(renderer) {
+	// Save state
+	this.renderer = renderer;
+	// Generate child nodes
+	this.generate();
+};
+
+InfoWidget.types = {
+	changecount: function(options) {return options.wiki.getChangeCount(options.title);}
+};
+
+InfoWidget.prototype.generate = function() {
+	// Get attributes
+	this.tiddlerTitle = this.renderer.getAttribute("tiddler",this.renderer.getContextTiddlerTitle());
+	this.type = this.renderer.getAttribute("type","changecount");
+	// Get the appropriate value for the current tiddler
+	var value = "",
+		fn = InfoWidget.types[this.type];
+	if(fn) {
+		value = fn({
+			wiki: this.renderer.renderTree.wiki,
+			title: this.tiddlerTitle
+		});
+	}
+	// Set the element
+	this.tag = "span";
+	this.attributes = {};
+	this.children = this.renderer.renderTree.createRenderers(this.renderer.renderContext,[{
+		type: "text",
+		text: value
+	}]);
+};
+
+exports.info = InfoWidget;
+
+})();