Returns an Output for the terminal specified in UnixSettings.
The specific output implementation chosen is based
on the TERM environment variable and ultimately
uses Graphics.Vty.Platform.Unix.Output.XTermColor
for terminals that look xterm-like or
Graphics.Vty.Platform.Unix.Output.TerminfoBased as a fallback
otherwise.
If
TERMstarts withxterm,screen,rxvt, ortmux, this will thexterm-based implementation.Otherwise this will use the
TerminfoBasedimplementation.