* Did some reviewing, turns out there's literally no reason to disable...

* Did some reviewing, turns out there's literally no reason to disable savemoddata when majormods gets tripped and it's just a stupid thing vanilla did for modifiedgame for some reason that we almost inherited with our new solution?
* Adjusted the save system to acknowledge the new status quo. Instead of trying to save modifiedgame in the file like some sort of extremely boneheaded honour system everyone and their mothers hacks around, we just use it to determine whether the save is for a mod with savedata or not (this keeps backwards compatibility based on how we were using it, anyways, especially with the *force* parameter...)
* Added a menu message for attempting to play a demo set on a map that isn't loaded, as opposed to letting it I_Error.
* Minor tweaks to addons menu representing modded status.