The new taglink.py app created links from all uses of TAGS

The new taglink.py app created links from all uses of TAGS
to the their definition.
The commit shows all these.
In addition I noted an erroneous FIXME (the text was
already complete) and deleted it.
A couple places used the ascii double-quote symbol, those
are now changed to the latex-standard `` and '' symbols.
Modified the python tests very slightly for better coverage
so modified the expected results too.