added 'never' built-in type

Author: dg

src/PhpGenerator/PhpNamespace.php

@@ -29,7 +29,7 @@ final class PhpNamespace
 	private const KEYWORDS = [
 		'string' => 1, 'int' => 1, 'float' => 1, 'bool' => 1, 'array' => 1, 'object' => 1,
 		'callable' => 1, 'iterable' => 1, 'void' => 1, 'self' => 1, 'parent' => 1, 'static' => 1,
-		'mixed' => 1, 'null' => 1, 'false' => 1,
+		'mixed' => 1, 'null' => 1, 'false' => 1, 'never' => 1,
 	];
 
 	/** @var string */

src/PhpGenerator/Type.php

@@ -25,6 +25,7 @@ class Type
 		CALLABLE = 'callable',
 		ITERABLE = 'iterable',
 		VOID = 'void',
+		NEVER = 'never',
 		MIXED = 'mixed',
 		FALSE = 'false',
 		NULL = 'null',