[Doxygen-develop] Automatic image file dependency generation patch

[Robert J. E. <rob...@gm...>]

This patch adds the HTML_IMAGE_DEPENDENCY_FILE_NAME and
LATEX_IMAGE_DEPENDENCY_FILE_NAME tags.  For each of these tags that
are defined, warnings about missing image files will be supressed (for
the related output type --- i.e. LaTeX or HTML), and a list of used
image files will be saved as prerequisite to a relevant make rule in a
make file named by the value of that tag.

For usage examples, see the included doxygen comments in the patch.

Please note that we included changes made to the file
optionsconfig.cpp although it is automatically generated from the
config.xml file.  We did this since that file is under revision
control (you might want to change that).

Regards Robert Jørgensgaard Engdahl and Anders Franz Terkelsen

p.s. We sent this patch previously, but since the sender address was
not on the mailing list the mail did not get through. I hope that we
are not offending anyone by sending this patch again.