Add support for relative dates

Including: setting date on save tiddler and adding a date to HelloThere

core/modules/macros/navigator.js

@@ -127,7 +127,12 @@ exports.eventMap["tw-SaveTiddler"] = function(event) {
 			var tiddler = this.wiki.getTiddler(event.tiddlerTitle);
 			if(tiddler && $tw.utils.hop(tiddler.fields,"draft.title")) {
 				// Save the draft tiddler as the real tiddler
-				this.wiki.addTiddler(new $tw.Tiddler(tiddler,{title: tiddler.fields["draft.title"],"draft.title": undefined, "draft.of": undefined}));
+				this.wiki.addTiddler(new $tw.Tiddler(tiddler,{
+					title: tiddler.fields["draft.title"],
+					modified: new Date(),
+					"draft.title": undefined, 
+					"draft.of": undefined
+				}));
 				// Remove the draft tiddler
 				this.wiki.deleteTiddler(event.tiddlerTitle);
 				// Remove the original tiddler if we're renaming it

core/modules/macros/view/viewers/relativedate.js

@@ -0,0 +1,27 @@
+/*\
+title: $:/core/modules/macros/view/viewers/relativedate.js
+type: application/javascript
+module-type: fieldviewer
+
+A viewer for viewing tiddler fields as a relative date
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+function renderValue(tiddler,field,value,viewMacro) {
+	if(value === undefined) {
+		return $tw.Tree.Text("");
+	} else {
+		return $tw.Tree.Text(
+			$tw.utils.getRelativeDate((new Date()) - value).description
+		);
+	}
+}
+
+exports["relativedate"] = renderValue;
+
+})();