Default content selection inside newly added expansions broken

[on3iro]

Content inside newly added expansions should be checked on by default.
However, because we fetch the users selection and fully overwrite each entities state (cards, nemesis, mages...), the content will always be checked off.

We need to find a simple way to address this, so users don't need to check on newly added content all the time (apart from checking the expansion itself).

#371 remedies this a bit, as its just one more click to activate content, so we should probably implement that one first, before we go for the fix here.