extract strings from arbitrary formats into PO files

 When using GNU gettext you often find yourself extracting translatable
 strings from more or less exotic file formats that cannot be handled by
 xgettext from the GNU gettext suite directly.
 .
 Locale::XGettext simplifies the task of writing a string extractor in Perl,
 Python, Java, Ruby or other languages by providing a common base needed
 for such scripts.
 .
 Included is a sample string extractor xgettext-txt for plain text files. It
 simply splits the input into paragraphs, and turns each paragraph into an
 entry of a PO file.
 .
 See also:
  https://github.com/gflohr/Locale-XGettext
  https://www.gnu.org/software/gettext/manual/html_node/PO-Files.html