New (compact) Design for the left Part and the Chat

Gives us the opportunity to choose a design that is more compact.

What I mean: TeamSpeak 3 is kept relatively compact. At the moment you have to have the entire window open, even if you only need the left area of Discord (especially voice channels). If you then need the chat, you could simply open it at the push of a button to be able to chat. Then you can close it again so that Discord is generally more compact.