can edit page index of bookmark when the page index is not NSNotFound, e.g. can't edit bookmarks for notes documents
can edit page index of bookmark when the page index is not NSNotFound, e.g. can't edit bookmarks for notes documents

git-svn-id: 765db44a9620ed55f4f8addfd3c14fe8cd57f6bb@6555 0fceea05-a30d-0410-8a8b-80ef821fb0a1

nanoant/Skim,nanoant/Skim,nanoant/Skim,nanoant/Skim,nanoant/Skim