[ESS] Hyperlinks in help pages

[Richard M. Heiberger]

Thank you Tom for detecting that.  I will confirm that the
workaround works correctly.

The underlying problem turns out to be that the test for whether
we are running the inferior ess process in an emacs buffer (R and
S-Plus Sqpe) or in an independent GUI process (S-Plus GUI) isn't
precise enough.  It will take some time for me to figure out how
to refine that test.  My goal is that your workaround will not be
needed in the next ESS release.

Rich