Enhance cl_voipSendTarget to accept also 'team'

[kai-li-wop]

In addition to #143 we could enhance cl_voipSendTarget to accept also 'team' as value globally. This should create a list of client numbers of the current list the player is playing in. If there is no team match going on, it could be reset to spatial internally. If this is not feasible, it might be useful to enhance the code of the ingame voice chat to create a team client list and inly to add the option there. It looks like the send target 'team' was never working as I cannot find any code handling it.

[ghost]

The reason why 'team' is supported only by a few idtech 3 games is that most implementations are invoking API breaking changes.
I think for WoP this isn't a big issue, though, I'm no maintainer, so this is up to you.
For reference:
ioquake/ioq3#334
darklegion/tremulous@a4d08a3
Tremulous supports the 'team' setting.
Currently I don't know in which status WoP's VOIP feature is at all. There seems to be some unfinished parts, eventually already meant for being used for the 'team' setting. PadWorld-Entertainment/worldofpadman-fork#138