Doxygen changes in postfix.h mostly formatting & adding tags.
Rec-ref changes regrouped the operators to match the order in
postfix.h, formatting, and added some missing operators.
Updated description of calcout.OEVT for named events.
In some cases the license-identification header was missing,
so I added that as well. Replaced the remaining headers that
specifically identified "Versions 3.13.7 and higher".
Makefiles and the build system were deliberately excluded.
