Custom Waypoints

THIS IS ONLY FOR PAPER / SPIGOT SERVERS

* @a waypoints are now one copy on the server: players who join later get them too
* Timers of @a waypoints run once, so everybody sees the same time
* The waypoint list is also sent when the client registers the channel, which fixes new players getting nothing
* Removing an @a waypoint from one player hides it only for them, also after they reconnect
* Added /waypointplugin animate and gradient for figures
* Added /waypointplugin paste and copy with the same text format as the client
* Added /waypointplugin background multiline
* Added live editing from the client editor with Set to everyone (needs customwaypoints.admin)
* Figures keep their border, animations and gradients, and text keeps its line spacing and per-line backgrounds