[pulseaudio-discuss] make pacmd less chatty

[Peter Meerwald]

I got annoyed by the extra output (welcome message, prompt) of pacmd
when using the program for scripted testing. This patch series adds
a --quiet option to pacmd and tries to sense when interactive prompting
is not needed (no terminal connected).

The implementation details are ugly (huge rework of the cli function to
include state) and a new cli command, hello, to actively request the
welcome message shown by pacmd in interactive sessions.