v1.1.0

Added

• srcdist Makefile target: produces a source archive
  dist/pbrenamer-<ver>-src.tar.gz via git archive
• tools/git_version.sh: derives the version string from the exact Git tag
  when HEAD is tagged and the working tree is clean, falls back to dev;
  used by both dist and srcdist targets

Changed

• i18n toolchain replaced: xgettext/msgmerge/msgfmt/msginit removed in
  favour of pybabel extract/update/compile/init; babel.cfg mapping
  file added; gettext dependency replaced by babel in environment.yml

Removed

• .mo compiled catalogues removed from the repository (now gitignored); the
  CI regenerates them via pybabel compile before each PyInstaller build