Cleaner Filter process for end user

[BiglifeMatt]

It would be nice to have a way to control the Filter page in settings so that the Inactive and Managesieve options could be hidden. It would even be better if the rainloop.user option could be automatically triggered when clicking on the Filters menu. That way the Edit Script: Rainloop.user window could just be the contents of the Filter page. That would make that so much easier for end.users to navigate and for them to not mess anything up in their settings.