bug#16781: 24.3; bibtex required fields

[Per Starbäck]

In GNU Emacs 24.3.1,
bibtex-biblatex-entry-alist in lisp/textmodes/bibtex.el tells about
required and optional fields in biblatex, refering to biblatex
documentation.

In the development version of biblatex this was recently changed in the edit
https://github.com/plk/biblatex/commit/b23f504d9138feb4faa2148de6e059d43c43405c

This diff follows suite for Emacs:

----------------------------------------------------------------------
$ diff -u /local/src/emacs-24.3/lisp/textmodes/bibtex.el bibtex-fixed.el
--- /local/src/emacs-24.3/lisp/textmodes/bibtex.el      2013-01-01 
21:37:17.000000000 +0100
+++ bibtex-fixed.el     2014-02-17 17:06:19.147293472 +0100
@@ -546,9 +546,9 @@
       ("location") ("isbn") ("pagetotal") ("addendum") ("pubstate") ("doi")
       ("eprint") ("eprintclass") ("eprinttype") ("url") ("urldate")))
     ("InCollection" "Article in a Collection"
-     (("author") ("editor") ("title") ("year" nil nil 0) ("date" nil nil 0))
+     (("author") ("title") ("year" nil nil 0) ("date" nil nil 0))
      (("booktitle"))
-     (("editora") ("editorb") ("editorc") ("translator") ("annotator")
+     (("editor") ("editora") ("editorb") ("editorc") ("translator") 
("annotator")
       ("commentator") ("introduction") ("foreword") ("afterword")
       ("subtitle") ("titleaddon") ("maintitle") ("mainsubtitle")
       ("maintitleaddon") ("booksubtitle") ("booktitleaddon")
@@ -616,10 +616,11 @@
       ("addendum") ("pubstate") ("doi") ("eprint") ("eprintclass")
       ("eprinttype") ("url") ("urldate")))
     ("Proceedings" "Single-Volume Conference Proceedings"
-     (("editor") ("title") ("year" nil nil 0) ("date" nil nil 0))
+     (("title") ("year" nil nil 0) ("date" nil nil 0))
      nil
      (("subtitle") ("titleaddon") ("maintitle") ("mainsubtitle")
       ("maintitleaddon") ("eventtitle") ("eventdate") ("venue") ("language")
+      ("editor")
       ("volume") ("part") ("volumes") ("series") ("number") ("note")
       ("organization") ("publisher") ("location") ("month")
       ("isbn") ("chapter") ("pages") ("pagetotal") ("addendum") ("pubstate")
@@ -633,9 +634,9 @@
       ("isbn") ("pagetotal") ("addendum") ("pubstate")
       ("doi") ("eprint") ("eprintclass") ("eprinttype") ("url") ("urldate")))
     ("InProceedings" "Article in Conference Proceedings"
-     (("author") ("editor") ("title") ("year" nil nil 0) ("date" nil nil 0))
+     (("author") ("title") ("year" nil nil 0) ("date" nil nil 0))
      (("booktitle"))
-     (("subtitle") ("titleaddon") ("maintitle") ("mainsubtitle")
+     (("editor") ("subtitle") ("titleaddon") ("maintitle") ("mainsubtitle")
       ("maintitleaddon") ("booksubtitle") ("booktitleaddon")
       ("eventtitle") ("eventdate") ("venue") ("language")
       ("volume") ("part") ("volumes") ("series") ("number") ("note")
----------------------------------------------------------------------

There is actually nothing in biblatex that upholds this distinction
between required and optional arguments, so it's only a documentation
thing, and (as the documentation says), the bibliography styles can
actually handle data very well that lack for example these "required"
fields.

Because of that there's no need to wait for a released version
where this documentation change has taken place, I think. The biblatex
issue is at https://github.com/plk/biblatex/issues/199 for more details
about this.