PacketNameTagTeams

Client-only scoreboard teams that keep a living entity's name tag visible to a viewer while something rides that entity. Minecraft hides the name of a team-less vehicle; an entity on a team follows the team's name-tag rule instead, so each kept subject gets a one-member team with nameTagVisibility ALWAYS on the viewer's client only. Mobs still show their name only when it is set visible or looked at, as without a rider. Callers release a subject while it has a real team on the viewer's Bukkit scoreboard.

Other plugins also send teams straight to clients, invisible to the Bukkit scoreboard. Moving their member into our team makes their later "remove this member" packet fail on the client, which disconnects the viewer. So each viewer's packet handler mirrors every team packet the client receives: a subject already on another team is not kept, and an entry our team held is put back into the sender's team just before such a removal reaches the client.