Add new class for auto set vars to certain types or null

Convert\VarSetType for always return type expected (eg string will be string)
or Convert\VarSetTypeNull to return string or null on failure

The return value for failure if not matching type can be set for both, but
only for Convert\VarSetTypeNull the return value can be set to null.

www/vendor/composer/autoload_psr4.php

@@ -2,7 +2,7 @@
 
 // autoload_psr4.php @generated by Composer
 
-$vendorDir = dirname(dirname(__FILE__));
+$vendorDir = dirname(__DIR__);
 $baseDir = dirname($vendorDir);
 
 return array(