Use Streams interface for xsl info/warings/errors

[siefkenj]

Python supports Streams which allow for forwarding data as it arrives.

It would be nice if the CLI could filter/group warnings and info that is generated by the XSL. One way to do this would be if pretext core produced a stream rather than writing to stdout/stderr.

@oscarlevin Would a stream help the CLI make the output more friendly?

[rbeezer]

Perhaps related: XSL processing log is now communicated better. Comments on the CLI side:

PreTeXtBook/pretext-cli#689

Code:

512775a

Beautiful error messages are not a priority. Complete, helpful, robust messages are. There's lots of room for improvment here, something I started to work on back in Ann Arbor, June 2022.

We use threads to communicate the XSL log on-the-fly. Maybe streams would be just as good, and better for other aspects. But unlikely to bubble-up in my queue anytime real soon.