command zone cast count trackers

[lyonhaert]

• could be separate object type that is created in the CZ v-stack.
• creation could be triggered manually from a card in the CZ, or perhaps by the first time a card is dropped into the CZ.
• should only allow creation if no other cast count tracker for the same card name is already there.
• need to be able to +/- the cast count, and need to be able to delete them.