Better testing.
- New provider, extracting bib and igt from CLDF datasets.
- Adapt to newer langsci and more glossa publications.
- Drop Python 3.7 compatibility.
- Adapt to imtvault v1.1
- Adapted langsci provider to new langsci catalog format.
- Registered more langsci publications without tex source.
Fixed bug whereby citation keys in the merged bib may have contained commas, making the resulting BibTeX invalid.