Exclude already seen cards

[tvqt]

(Maybe I've just been playing the game too much) but it would be nice to have an option of excluding cards that have been seen before- I tend to see the same cards come up quite often, so it would be neat to have an option of making sure that this doesn't happen

[tom-james-watson]

I think the best way to combat this is to simply have more cards! That's not a simple change though, it would require reworking the generator (https://github.com/tom-james-watson/wikitrivia-generator).