bug#16781: 24.3; bibtex required fields

[Per Starbäck]

Glenn Morris wrote:
> Oh, duh, I get it now. You were talking about biblatex; for some
> inexplicable reason I thought you were talking about biblatex.el.
> I have no idea why I thought that...

I'm glad that confusion is over before I had time to reply.

> So I'm not sure whose github repository that is, nor why it says: "This
> is the current home of biblatex as the status of the author of biblatex
> is currently unclear."

Since those not into biblatex may wonder if this is the real deal I
should add here that it is indeed. This is what is part of CTAN and what
is distributed to TeX distributions like Tex Live and MikTeX.

My proposed change are about fields there always were optional in
bibtex, and are therefore are omitted in most bib files.

Even though biblatex always have managed without them just as fine as
bibtex its documentation (until now) said they were required, so
bibtex-biblatex-entry-alist requires them, and therefore (with default
settings) refuses to add entries without them.