Send all output through a common subroutine

Use a common subroutine for all console output. Pass it the stream as
well since we want the output to go to different streams.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>
Add quiet flag to turn off output

We have a flag that turns on verbose output, but nothing that turns all
output off. Add the quiet flag and suppress output when it's enabled.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>