Custom merging:
* .po files
* NEWS files
* ChangeLog
* https://pypi.org/project/xmldiff/
* python with libCST
* Clang
* CSV
 + https://github.com/tabbyrobin/csvdove
 + https://github.com/defcube/csvmerge

Preprocessing
* gzip
* Diffoscope

Normalize
* clang-format
* Black
* go-format

Regenerate from source
* configure.ac / configure.in => configure
* Makefile.am => Makefile
* Makefile.in => Makefile
