Module activation enables simplefog for all scenes

[UranusBytes]

As reported by @jasonxbergman

I ran a session over the weekend with the preliminary v10 version. It works, but it looks like once the module is activated it's turning simplefog on for ALL scenes, and you have to manually disable it for ones where you don't want it.

I use SF for some, but not every scene.

As confirmed by @HenningTimm

Each time I reload the world, Simplefog activates on all scenes and needs to be manually turned off for scenes that should not use it. The migration seems to have worked fine.

#78 (comment)