Make page rotation and crop undoable. Don't change the document change count, as this is not persistent. 
Make page rotation and crop undoable. Don't change the document change count, as this is not persistent. 

git-svn-id: 765db44a9620ed55f4f8addfd3c14fe8cd57f6bb@2102 0fceea05-a30d-0410-8a8b-80ef821fb0a1

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