Implement a plan for splitting up the master sheets

[Asmor]

I'm no longer intending to update the master sheets, with the possible exception of major official content (new Monster Manuals or things like Volo's, for example).

I've updated the sheet checker so it can add content directly from itself and it can also generate shareable links.

I'd like to break the existing content apart into additional sheets which people can add or not. Problem is I can't just remove that content from the master sheets without finding a way to replace it, or it will wipe out everyone's saves.

Ideally what I'd like to do is...

1. Determine if someone is using the old master sheets
2. If they are, figure out which content specifically they've got saved currently
3. Automatically add the new sheet IDs for those specific content
4. Remove the master sheets from their cache

I suspect there are probably some nasty gotchas so I don't want to rush forward with implementing a solution; I've also used up all my motivation for the time being and the current status quo is working so I don't feel any pressing need to implement this ASAP.