Link to Org file: regard startup view state

Link to Org file: regard startup view state

* lisp/org.el (org-open-link-from-string): Regard `reference-buffer'
when setting `org-inhibit-startup'.

When opening a link to another Org file not yet opened (first close it
if opened) before this patch:
1) When point is on the line with the link and the line is not a
   heading then the target file is opened with the target file startup
   view state, e. g. the default OVERVIEW.
2) When point is on the heading of the entry of which the link is part
   of then the target file is opened with "SHOW ALL". But it is
   expected to regard the target file startup view state like case 1).
Note: Only in case 2) `org-open-at-point' uses
`org-offer-links-in-entry' and from there `org-open-link-from-string'.

example current buffer with link:
#+BEGIN_SRC org
  ,* section
  ,  [[file:myfile.org::*mytarget]]
#+END_SRC

example target file myfile.org:
#+BEGIN_SRC org
  ,* mytarget
  ,  text
  ,*** subsection
#+END_SRC