Automatically load PlatformSettings.php
Also remove ``//require_once "$IP/includes/PlatformSettings.php";` lines
It seems that this is no longer required by the dev image that we are using (it used to be) So we can remove the confusing commented out line in the start of generated local settings files. This also means that !436 (merged) work out of the box, wgArticlePath must have changed in core (or got removed), and it is needed for /wiki redirects to work correctly.