* Client-server architecture. All clients send their output to the
  server, while it copies it to other clients. However, as a rule, there
  is single client speaking at one time.
* 20ms frames with Opus-encoded audio with PLC (Packet Loss Concealment)
  and DTX (discontinuous transmission) features enabled. Optional [VAD]
  (voice activity detection).
  => Opus codec
* Noise-NKhfs protocol-based 0-RTT single round-trip handshake over TCP
  between client and server for creating authenticated encrypted channel
  and authentication based on server's public key knowledge.
  => Noise protocol framework
  => KEM-based hybrid forward secrecy
* Fast ChaCha20 encryption with SipHash24 message authentication.
* Rooms, optionally password protected. Peers are able to broadcast
  text message to everyone in the room.
* Ability to silence specified peer in the room.
* Fancy TUI client with mute-toggle ability by external utilities.