Add support for autosave

Causes the wiki to be autosaved whenever clicking “done” after editing
a tiddler. Only works with savers that support autosave. We should
probably make autosave configurable

core/modules/widgets/navigator.js

@@ -289,6 +289,8 @@ NavigatorWidget.prototype.handleSaveTiddlerEvent = function(event) {
 				if(draftTitle !== this.storyTitle) {
 					this.saveStoryList(storyList);
 				}
+				// Send a notification event
+				this.dispatchEvent({type: "tw-auto-save-wiki"});
 			}
 		}
 	}