prepared the 2.4.7 release

CHANGELOG

@@ -1,4 +1,4 @@
-* 2.4.7 (2018-XX-XX)
+* 2.4.7 (2018-03-20)
 
  * optimized runtime performance
  * optimized parser performance by inlining the constant values

lib/Twig/Environment.php

@@ -16,12 +16,12 @@
  */
 class Twig_Environment
 {
-    const VERSION = '2.4.7-DEV';
+    const VERSION = '2.4.7';
     const VERSION_ID = 20407;
     const MAJOR_VERSION = 2;
     const MINOR_VERSION = 4;
     const RELEASE_VERSION = 7;
-    const EXTRA_VERSION = 'DEV';
+    const EXTRA_VERSION = '';
 
     private $charset;
     private $loader;