Remove usage of non existent style.css

The file was actually removed in 2813829 
as part of the modern UI conversion.

Fixes #257

Author: atrol

Source/Source.php

@@ -110,7 +110,6 @@ function events() {
 	function hooks() {
 		return array(
 			'EVENT_CORE_READY' => 'core_ready',
-			'EVENT_LAYOUT_RESOURCES' => 'css',
 			'EVENT_MENU_MAIN' => 'menu_main',
 			'EVENT_FILTER_COLUMNS' => 'filter_columns',
 		);
@@ -165,10 +164,6 @@ function filter_columns()
 		);
 	}
 
-	function css() {
-		return '<link rel="stylesheet" type="text/css" href="' . plugin_file( 'style.css' ) . '"/>';
-	}
-
 	function menu_main() {
 		$t_menu_options = array();