int PS_add_bookmark(PSDoc *psdoc, const char *text, int parent, int open)
Adds a bookmark for the current page. Bookmarks usually appear
in PDF-Viewers left of the page in a hierachical tree.
Clicking on a bookmark will jump to the given page.
parent is another bookmark
which is used as the parent of the new bookmark. If
open is unequal to zero the bookmark will
be shown open by the pdf viewer.
The bookmark has no meaning if the document is printed or
viewed but it will be used if the document is converted to pdf by either
Acrobat Distiller™ or Ghostview.
The returned value is a reference for the bookmark. It is only
used if the bookmark shall be used as a parent.