Refactored tests to use a sample project.
Updated extraction:
* Removed special handling of single percent signs.
* When extracting messages from template text, doubled all percent signs
so they are not interpreted by gettext as string format flags. All
strings extracted by gettext, if containing a percent sign, will now
be labeled "#, python-format".
Updated translation:
* Used "%%" for "%" in template text before calling gettext.
* Updated {% trans %} rendering to restore "%" from "%%".
Make sure PO catalog text fetched from gettext programs via standard
output isn't corrupted by mismatch between assumed (UTF-8) and real
(CP1252) encodings. This can cause mojibake to be written when creating
or updating PO files.
Also fixes#23311.
Thanks to contributor with Trac nick 'danielmenzel' for the report,
excellent research and fix.
Instead of crashing with a CommandError, now a non-writable location
of mo files will only make compilemessages complain and continue.
Thanks Ramiro Morales for the review.
Fixes#19584.
This implies stop storing file path command line arguments in envvars as
a security measure to start relying on with Popen's shell=False instead,
and addition of an 'utils' module.
Thanks kmichel_wgs for the report.
