New features, bug fixes, optimization

- Waypoints can now be enabled/disabled with "/wp toggle". Disabled
waypoints will show up in list as disabled. Players with "wp.bypass"
permission will still be able to travel to disabled waypoints
- Players with "wp.select" can left-click with a Waypoint Beacon to
select waypoints. Enabling/disabling the beacon no longer requires a
server restart to take effect.
- Reworked discovery mode to eliminate Vault soft-dependency and add
functionality: "Server-wide" will allow discovered waypoints to show up
globally. "World-specific" only allows discovered waypoint to show in
its own world. "Disabled" disables discovery mode
- Home waypoints now stored in new PlayerData class, which is needed for
storing discoveries
- Database class renamed to Data; methods are now static
- Fixed bug that allowed player to drop items from directory under rare
circumstances