Make editing arena spawns easier

[jwflory]

Currently, it is difficult for a server administrator to edit an arena's spawns once they have been set, which can make fixing a bad spawnpoint difficult. This is a double-pronged enhancement suggestion:

Make spawnpoints temporary visible

By typing a command, it would be convenient for a server administrator to get a visual representation of all the spawnpoints on a map by replacing each spawnpoint with a piece of glass for a duration of about five seconds or so. If this is not feasible at the moment, a list of all spawnpoints with spawnpoint ID numbers and specific coordinates would be fine just as well.

Make spawnpoints removable

There should also be a way to directly remove spawnpoints after they are created via a command.