[GNC] gncJobNextID in gncJob.c not in gncJob.h

[Robert Simmons]

Another observation: the current GnuCash mixes data and display layers.

For a new system, I would suggest separating everything completely. Have a
database and lib layer that interacts with the database. Then expose the
lib to C, Python, C++, Rust, Go, whatever. You can then have a REST layer
built on one of those. Then a GTK display layer (what GnuCash is now) would
be built against the API. And a web layer can be built against the REST API.