Server:
ROAR_DRIVER	by server init
ROAR_DEVICE	by server init
DMX		by dmx driver

Client:
ROAR_PROXY	by sockets
socks_proxy	by sockets
http_proxy	by sockets
https_proxy	by sockets
ssh_proxy	by sockets
TERM		by password API
DISPLAY		by password API
CDDA_DEVICE	by CDDA API

Both:
HOME		by basic API, autodetection
ROAR_SERVER	by basic API, server init
ROAR_OPTIONS	by config API
USER		by sockets, autodetection

Compatibility layers:
AUDIODEVICE	by sndio
MIDIDEVICE	by sndio
PULSE_SERVER	by pulseaudio
