Invitation

• Fixed /whitelist list showing "null" for invited players who have never joined the server.
• Ordered usernames by date, so now you will always be able to see the /invitelog of recently joined players instead of stale entries.
• Added pagination to /invitelog. You can now page through five entries at time.
• Added filters for /invitelog to search invite log by most recent, by who invited a player, and by who a player invited.
• Added /uninvite to allow normal players to revoke an invitation.
• Added config option cooldown-seconds to configure cooldown between /invite that hit the Mojang API.
• Added config option undo-seconds to configure the length of the window in which /uninvite works.

Warning: there is a migration for the invite log database in this update. A backup file (invites.db.bak) will be created beforehand, but you should keep your own backup just in case.