Add comment linking to Maniphest and Differential

Summary:
Allows you to link to comments with "D123#3" or "T123#3", then adds a pile of JS
to try to make it not terrible. :/

The thing I'm trying to avoid here is when someone says "look at this!
http://blog.com/#comment-239291" and you click and your browser jumps somewhere
random and you have no idea which comment they meant. Since I really hate this,
I've tried to avoid it by making sure the comment is always highlighted.

Test Plan:
Put T1#1 and D1#1 in remarkup and verified they linked properly.

Clicked anchors on individual comments.

Faked all comments hidden in Differential and verified they expanded on anchor
or anchor change.

Reviewed By: aran
Reviewers: aran, tomo, mroch, jungejason, tuomaspelkonen
CC: aran, epriestley
Differential Revision: 383

src/applications/auth/controller/login/PhabricatorLoginController.php

@@ -42,7 +42,7 @@ class PhabricatorLoginController extends PhabricatorAuthController {
     $error_view = null;
     if ($password_auth) {
       $error = false;
-      $username = $request->getCookie('phusr');
+      $username_or_email = $request->getCookie('phusr');
       if ($request->isFormPost()) {
         $username_or_email = $request->getStr('username_or_email');