Documentation fixes

I  have four  documentation patches  ready for  review that  came from
looking at  the doxygen  error output.   The first  is the  upgrade to
Doxyfile,  the other  three are  small  fixes to  errors that  doxygen
happened  to  notice.  I  hope  the  extended descriptions  will  make
everything clear.

    http://starurchin.org/dillo/patch/doxygen-upgrade-config.html
    http://starurchin.org/dillo/patch/doxygen-remove-unmatched-close-div.html
    http://starurchin.org/dillo/patch/doxygen-typo-nsbp-entity.html
    http://starurchin.org/dillo/patch/doxygen-escape-button-tag-angle-brackets.html

There is more to do but I'd like to clear these out of the way first.

All comments are welcome.

Regards,

Jeremy Henty