build: Add creation of Doxygen docs to build system * configure.ac: Add doc/doxyhtml/Makefile to list of Makefiles to generate. * Doxyfile: Moved and renamed to doc/doxyhtml/Doxygen.cfg. * doc/Makefile.am: Add doxyhtml directory to list of SUBDIRS. * doc/doxyhtml/Doxygen.cfg: Renamed from Doxyfile at top-level. * doc/doxyhtml/Makefile.am: New Makefile.am with rules for building and cleaning Doxygen documentation * doc/doxyhtml/README: README file explaining how to build optional Doxygen documentation.

This directory contains documentation in Doxygen format for
Octave's source code.  It is not created by default.

To produce Doxygen documentation use

make doxyhtml

Doxygen documentation can be helpful for developers of Octave, but is not
needed by users of Octave.  In addition, the documentation requires
approximately 1.2GB of storage space.  For these reasons it is not maintained
under version control nor distributed in tarballs.