[Feature] Lobby interface improvements: Custom team names

[albertz]

Converted from SourceForge issue 3290831, submitted by nubsis

Allowing the host to set team names would be allowing custom team names. This would be used by clans and similar to show who is playing and also be of use for a ranking system or similar. Ordering players by teams in the lobby would leverage this feature. The GameMode class already has support for getting team names, so the interface could allow the host to set the team name. Incompatible clients might not be aware of a different team name, however.