Change AC_PROG_77 to AC_PROG_FC.
I do this slightly tentatively, because (a) this directory notes that
its contents 'could do with some modernisation', and (b) it's a demonstration
setup, which might therefore be slightly odd in other ways.  All that said,
this change doesn't obviously break anything....
Change DIY \ifpdf to \usepackage{pdf}
we can by now (2014) assume that this package will be
present in any half-way reasonably up-to-date TeX installation.
rolling our own just causes breakage when some other package includes
ifpdf, which hyper-cautiously bails out if it finds \ifpdf
already defined.
Tweaks to get SSN/78 to build
There were relics of Subversion in ssn78.xml (ie $Revision$),
which (because $Date$ isn't a valid date) ended up preventing it being
processed -- fixed by hand, with a recent Git revision.

Also, the .png and .gif files in the directory seemed to be
out of sync with each other for some probably-Makefile-related reason.
Merge branch 'master' of github.com:Starlink/starlink