Allow profile menus to be collapsed and expanded

Summary:
Ref T10054. I think this gets everything except:

  - circles on icons;
  - I spent ~15 minutes poking at animations but wasn't able to get anything that looked reasonable whatsoever.

Test Plan:
  - Collapsed menus.
  - Expanded menus.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10054

Differential Revision: https://secure.phabricator.com/D15056

src/applications/project/controller/PhabricatorProjectPanelController.php

@@ -12,10 +12,13 @@ final class PhabricatorProjectPanelController
     $viewer = $this->getViewer();
     $project = $this->getProject();
 
-    return id(new PhabricatorProjectProfilePanelEngine())
+    $engine = id(new PhabricatorProjectProfilePanelEngine())
       ->setProfileObject($project)
-      ->setController($this)
-      ->buildResponse();
+      ->setController($this);
+
+    $this->setProfilePanelEngine($engine);
+
+    return $engine->buildResponse();
   }
 
 }