feat: issue2551287 - roundup-gettext extracts strings from detectors/extensions Enhance roundup_gettext.py to extract strings from detectors/extensions. If the polib module is available, roundup-gettext will extract translatable strings from the tracker's Python code. If polib is missing, it will print a warning. Marcus did most of the work, I had to do a python 2-> conversion of pygettext.py.