Declare new PROJECT_DIR variable

This points to the source directory of the project where the test suite has been installed

Author: swissspidy

features/bootstrap/FeatureContext.php

@@ -209,8 +209,9 @@ private static function get_behat_internal_variables() {
 		}
 
 		$variables = [
-			'SRC_DIR'        => realpath( dirname( dirname( __DIR__ ) ) ),
 			'FRAMEWORK_ROOT' => realpath( $framework_root ),
+			'SRC_DIR'        => realpath( dirname(  __DIR__, 2 ) ),
+			'PROJECT_DIR'    => realpath( dirname(  __DIR__, 5 ) ),
 		];
 
 		return $variables;