* doc/Makefile.am (DOXYFILE)
	(DOXYFILE_USER_PDF, DOXYFILE_USER_HTML)
	(DOXYFILE_DEVEL_PDF, DOXYFILE_DEVEL_HTML):
	New variables.
	(USER_REFMAN_LATEX)
	(DEVEL_REFMAN_PDF, DEVEL_REFMAN_LATEX, DEVEL_REFMAN_HTML):
	New variables.
	(all-local): Depend on $(srcdir)/$(USER_REFMAN_PDF),
	$(srcdir)/user-refman-html.stamp.
	($(srcdir)/$(USER_REFMAN_PDF)): Split these targets and move the
	generation of the LaTeX sources...
	($(srcdir)/user-refman-latex.stamp)
	($(srcdir)/$(USER_REFMAN_LATEX))
	($(srcdir)/devel-refman-latex.stamp)
	($(srcdir)/$(DEVEL_REFMAN_LATEX)):
	...here (new targets).
	($(srcdir)/$(USER_REFMAN_HTML))
	($(srcdir)/$(DEVEL_REFMAN_HTML)):
	Delegate the actions to...
	($(srcdir)/user-refman-html.stamp)
	($(srcdir)/devel-refman-html.stamp):
	...these (new) targets.
	(clean-user-refman-latex, clean-user-refman-html)
	(clean-devel-refman-latex, clean-devel-refman-html):
	New (phony) targets.
	(maintainer-clean-local): Depend on clean-user-refman-latex,
	clean-user-refman-html, clean-devel-refman-latex and
	clean-devel-refman-html.
	(EXTRA_DIST): Disable Doxyfile_devel_html, Doxyfile_devel_pdf,
	Doxyfile_user_html and Doxyfile_user_pdf.
	Add $(DOXYFILE).in.
	($(srcdir)/Doxyfile_user, $(srcdir)/Doxyfile_user_pdf)
	($(srcdir)/Doxyfile_devel, $(srcdir)/Doxyfile_devel_pdf):
	Rename targets as...
	($(DOXYFILE_USER_HTML), $(DOXYFILE_USER_PDF))
	($(DOXYFILE_DEVEL_HTML), $(DOXYFILE_DEVEL_PDF)):
	...these.