Sending too many lobbyData messages

[Gcommer]

When clients send lobbyJoin, they tend to receive multiple redundant messages (described below) (all before the lobbyJoin response).

This includes (sometimes duplicated) copies of the lobbyData with them not in their old slot, and then (again, sometimes duplicated 2+ times) copies of the lobbyData with them in their new slot.

Interspersed are also multiple lobbyListData messages.