[REQUEST] [LSAR/UNAR] Print error messages to error stream

[kyeastmood]

When error messages are printed to error stream they are easier to parse by other tools. However currently they are sent to output stream.

It would be great to either do it automatically or allow the user configure the streams in the command. For instance in 7-Zip there is a -bs switch.
Syntax:

-bs{o|e|p}{0|1|2}

Where 7-Zip message types are:

o - standard output messages
e - error messages
p - progress information

And messages' destination streams are:

0 - disable stream
1 - redirect to stdout stream
2 - redirect to stderr stream

Examples:

# Tests archive.7z and sends error messages to stdout that is redirected to log.txt:
7z t archive.7z -bse1 > log.txt

# Tests archive.7z and sends progress information to stderr stream:
7z t archive.7z -bsp2 > log.txt

Thanks