Correct various spelling errors

Summary: Fixes T11477.

Test Plan: Grep for Mulitple

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T11477

Differential Revision: https://secure.phabricator.com/D16399

Author: Chad Little

src/applications/config/option/PhabricatorApplicationConfigOptions.php

@@ -234,7 +234,7 @@ final public static function loadAllOptions($external_only = false) {
         if (isset($options[$key])) {
           throw new Exception(
             pht(
-              "Mulitple %s subclasses contain an option named '%s'!",
+              "Multiple %s subclasses contain an option named '%s'!",
               __CLASS__,
               $key));
         }

src/applications/settings/setting/PhabricatorEditorMultipleSetting.php

@@ -9,7 +9,7 @@ final class PhabricatorEditorMultipleSetting
   const VALUE_SINGLE = 'disable';
 
   public function getSettingName() {
-    return pht('Edit Mulitple Files');
+    return pht('Edit Multiple Files');
   }
 
   public function getSettingPanelKey() {