LocalConf extension settings

[mikestreety]

Should we use LocalConfiguration.php and extension settings to enable/disable engines? That way we could have the AJAX one bundled, but disabled by default.

This would only alter the select box, rather than removing it from the EXTCONF array.

E.g.

Should it list engines to exclude (so all are enabled by default) or engines to include. I guess exclude so if you add a new, custom, one you don't then need to enable it in settings