Grouping improvements

[mbbush]

As I'm working on my major changes to source data from the wiki, I'm re-thinking the way we do grouping. I'd like to have it mostly driven by the type and the set, with a list of types that need grouping. Then add two extra attributes to the card_db: group_with and group_with_type. So Necromancer would get "group_with_type: Zombie" and Pasture would get "group_with: Shepherd", for example.

One part I haven't thought through is how to represent this in the options, and what the defaults should be. I could see some users wanting a separate divider for "Zombies" or "Page Upgrades", while others want them grouped with the kingdom card. I'm not sure if anyone would want separate dividers for each zombie and each traveller, but it's easy enough to implement that.

Landscape cards and unique-ish cards (Loot, Knights, Castles, Ruins, Shelters) I think should be grouped by default, with the ability to ungroup them.