flexicon 4.1.0

First release under the name flexicon (PyPI distribution: pyflexicon).

flexicon is now an independent successor to cdfarrow/flexlibs (LGPL-2.1 attribution retained), no longer maintained as a fork.

Install: pip install pyflexicon — import: import flexicon

• The legacy flexlibs2 import name still works as a deprecated alias (removed in v5.0.0); existing FlexTools / FlexTrans scripts keep running unchanged.
• Adds fill_gaps merge mode to ApplySyncableProperties.
• Packaging consolidated to pyproject.toml; license metadata corrected to LGPL-2.1-or-later.