card exists but doesn't

These may be broken into several separate tickets, but let's list what we'd like to see. Logging:

• log cardtype change
• log name changes
• log deletion/recreation

Changes tab:

• shift from current one-version-at-a-time to listing all versions back through time, both content and above-listed changes
• diff between arbitrary versions
• also list settings changes? (these are logged in the relevant cards, including permissions after we setting-ize permissions) Maybe only +*self settings changes? Hrm.