Write DynamicProgress bar to stderr

[Joyjit Daw]

Hello,

First off wanted to say this is a super nice tool :). Thanks for building it!

I noticed that the DynamicProgress bar only outputs to cout. Could we have an option to route it to cerr as well? My use case is I started with 2 bars which were both using Stream to write to cerr. But the Stream is not an option to DynamicProgress bar, so it would be great to have that.

Thank you!