optimize ajaxify

- do not call $.timeago twice on topic load and for widgets
- do not use toLocaleString for each timeago string, use a single
Intl.DateTimeFormat instance instead
- do not call format for empty timeago strings, ie a post that isnt
edited doesnt have a timeago string
- do not call isTouchDevice for every element
- remove app.replaceSelfLinks, this is superceded with /me route
- store references to jquery objects in navigator instead of creating
them on every scroll

public/src/client/topic.js

@@ -45,7 +45,7 @@ define('forum/topic', [
 
 		app.enterRoom('topic_' + tid);
 
-		posts.processPage(components.get('post'));
+		posts.onTopicPageLoad(components.get('post'));
 
 		postTools.init(tid);
 		threadTools.init(tid);