Move array_diff / array_values into different lines in MD_STD::scandir

This leads a significant reduction in RAM usage.

MD_STD.php

@@ -63,7 +63,13 @@ final class MD_STD {
             throw new MDFileDoesNotExist("There is no file {$filepath}");
         }
 
-        return \array_values(\array_diff($output, ['.', '..', '.git']));
+        // Remove unwanted files from list
+        $output = \array_diff($output, ['.', '..', '.git']);
+
+        // Return array values, to make it a list rather than an associative array.
+        // This should be done in a separate line, as it observably leads to a
+        // significant reduction in the used RAM.
+        return \array_values($output);
 
     }