Officially support multiple installations of Subliminal.

[wearhere]

This means reconciling installations of Subliminal's supporting file and trace templates--it's weird to have each installation uninstall and then install the templates. At a minimum, it would be nice to not reinstall the templates if they were identical to what was already there.

To truly support multiple installations of Subliminal, we would need to figure out what to do if the files were different, though.