Changes the ConfirmDelete page and updates database code.

The ConfirmDelete page now uses parts of the photopage. The
Confirmation dialog is its own template which is based on Alert.

The database now updates the album thumb to the most recent
addition to the album, when the album thumb asset is being deleted.
When there are no pictures left in the album 0 will be set.

models/Dispatcher.php

@@ -28,7 +28,6 @@ class Dispatcher
 			'suggest' => 'ProvideAutoSuggest',
 			'timeline' => 'ViewTimeline',
 			'uploadmedia' => 'UploadMedia',
-			'confirmdelete' => 'ConfirmDelete',
 		];
 
 		// Work around PHP's FPM not always providing PATH_INFO.