prepared the 1.35.4 release

CHANGELOG

@@ -1,4 +1,4 @@
-* 1.35.4 (2018-XX-XX)
+* 1.35.4 (2018-07-13)
 
  * ensured that syntax errors are triggered with the right line
  * added the Symfony ctype polyfill as a dependency

lib/Twig/Environment.php

@@ -16,12 +16,12 @@
  */
 class Twig_Environment
 {
-    const VERSION = '1.35.4-DEV';
+    const VERSION = '1.35.4';
     const VERSION_ID = 13504;
     const MAJOR_VERSION = 1;
     const MINOR_VERSION = 35;
     const RELEASE_VERSION = 4;
-    const EXTRA_VERSION = 'DEV';
+    const EXTRA_VERSION = '';
 
     protected $charset;
     protected $loader;