Created a preference pane for DarkConsole, instead of link

Summary: Just removed the link and created a new field under preferences. Now the setting is under Display Preferences.

Test Plan: Enablied/Disabled dark console to see if it works.

Reviewers: epriestley

Reviewed By: epriestley

CC: irinav, aran, Korvin

Maniphest Tasks: T2344

Differential Revision: https://secure.phabricator.com/D4549

Conflicts:

	src/view/page/PhabricatorStandardPageView.php

src/applications/base/controller/PhabricatorController.php

@@ -88,9 +88,12 @@ abstract class PhabricatorController extends AphrontController {
       return $this->delegateToController($checker_controller);
     }
 
+    $preferences = $user->loadPreferences();
+
     if (PhabricatorEnv::getEnvConfig('darkconsole.enabled')) {
-      if ($user->getConsoleEnabled() ||
-          PhabricatorEnv::getEnvConfig('darkconsole.always-on')) {
+      $dark_console = PhabricatorUserPreferences::PREFERENCE_DARK_CONSOLE;
+      if ($preferences->getPreference($dark_console) ||
+         PhabricatorEnv::getEnvConfig('darkconsole.always-on')) {
         $console = new DarkConsoleCore();
         $request->getApplicationConfiguration()->setConsole($console);
       }