mint-arena: Make TA voice chat head stick to left side in widescreen

The HUD is drawn centered, but voice chat head should always be at left side
so that console notify/chat text doesn't draw over it.
mint-arena: Don't offset notify text when voice chat head is not showing

Allow voice chat head to time out even when it's not being drawn.
Voice chat head is hidden when scoreboad is showing, so don't offset notify text.
mint-arena: Don't print voice chat message for local players not in game
mint-arena: Remove showing voice head in CG_PlayVoiceChat

The voice head menu is open/closed for each splitscreen viewport as needed.
mint-arena: Fix G_TeamCommand possibly sending to all teams

Must check if localPlayerNum is -1 (meaning player not in game) before using
it as an array index.