Request: org-display-outline-path report full file path even when narrowed

[gregory@dynapse.com (Gregory J. Grubbs)]

When the following file is narrowed to the "Sub Two" tree,
org-display-outline reports the path relative to "Sub Two".  It would be
more useful to report, e.g. "Top One/Sub Two/Blah" 

Obviously, if you are narrowed further down the hierarchy, the current
function becomes even less useful.

--8<---------------cut here---------------start------------->8---
* Top One
** Sub One
*** Sub Sub One
*** Sub Sub Two
** Sub Two
*** Blah
**** Forget following this pattern
*** Blah Blah
* Top Two
--8<---------------cut here---------------end--------------->8---

I would have submitted a patch, but my naive attempts to use (widen)
within a (save-excursion) did not work!

Cheers,
-Greg