Also cache children for notes and links for smaller page ranges, as assistive devices can request the children several times in a row. Invalidate in some more cases, eg when changing displaymode.
Also cache children for notes and links for smaller page ranges, as assistive devices can request the children several times in a row. Invalidate in some more cases, eg when changing displaymode.

git-svn-id: 765db44a9620ed55f4f8addfd3c14fe8cd57f6bb@3794 0fceea05-a30d-0410-8a8b-80ef821fb0a1

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