Disable ANSI output

[OrangeDog]

Even with TERM=dumb the tool still insists on full colour output and fancy progress bars.

This is very annoying when dealing with log files or CI systems.
There should be a specific option to disable fancy output, as well as respecting common environment variables and whether the output is a terminal, pipe, or file (e.g. via ncurses).

[OrangeDog]

It appears that some of the output is written direct to the terminal, not to stdout or stderr, which complicates things further.

Some, but not all, fancy output is disabled when stderr is redirected.