Fixed emacs font-lock issues in site-lisp/kpp.el

[yantosca]

In this PR we have used AI to "lint" the site-lisp/kpp.el file. Some of the emacs lisp commands in kpp.el were changed/updated in newer emacs versions and so this was causing rendering issues.

@RolfSander: Please test with your version of emacs and let me know if this works OK.

[RolfSander]

Thanks, @yantosca, I will check the new .el file. Please give
me some time...

[RolfSander]

I noticed that kpp.el still contains #WRITE_ATM,
#WRITE_MAT, #WRITE_OPT and #WRITE_SPC. Can they be deleted?

[RolfSander]

I found several other obsolete KPP commands and section names which
apparently were re-introduced by the AI: #DEFRAD, #INITIALIZE,
#LUMP, #RUN, #SETRAD, #SPARSEDATA, #TRANSPORTALL,
#TRANSPORT, #USES, #USE, #XGRID, #YGRID, #ZGRID.

[RolfSander]

Since the suffixes .def and .spc are also used for other (non-KPP)
files, the new code does not activate the KPP mode for these files
anymore. Do we want this change? I see two options:

1. We re-activate the KPP mode for all *.def and *.spc files. This
   should be fine if people who use our kpp.el know what they are
   doing.

2. Instead of activating the KPP mode automatically, we add the
   following header to all our *.def and *.spc files:

   // -*- kpp -*-

   With this option, non-KPP *.def and *.spc files won't be
   affected. However, we would have to remember in the future to always
   add this header to our new files. In addition, it means that we have
   an emacs-specific header in the files which is irrelevant when using
   a different editor.

I'm not sure what's better but I tend towards option 1.

[yantosca]

Thanks @RolfSander. Let's go with option 1.

[RolfSander]

OK, I'll re-activate spc and def.

[RolfSander]

Do you want me to delete the obsolete KPP commands and section names?

[RolfSander]

As there were no objections, I have removed the obsolete KPP sections
and commands again.

[RolfSander]

It works fine for me now.