Implement onCardPlayed, onOwnCardPlayed events and Wild Pyromancer to test it

Note that for now, we trigger this earlier than we should because Wild Pyro
should actually use an "after" event, but haven't figured those out yet.
Implement all missing GameTags used in card definitions
Add a script to check which cards are implemented
Implement Baron Geddon, Cairne Bloodhoof and Malygos
Implement Nat Pagle
Implement Mind Vision, with tests