AlbumButtonBox: add visual cue to indicate a filter is active

controllers/ViewPhotoAlbum.php

@@ -55,6 +55,7 @@ class ViewPhotoAlbum extends HTMLController
 			{
 				$filters[$contributor['slug']] = [
 					'id_user' => $contributor['id_user'],
+					'label' => $contributor['first_name'],
 					'caption' => sprintf('By %s (%s photos)',
 						$contributor['first_name'], $contributor['num_assets']),
 					'link' => $tag->getUrl() . '/?by=' . $contributor['slug'],