Search for DVI conversion tool in a class method on the main thread. Allows using NSFileManager and only searches once. 
Search for DVI conversion tool in a class method on the main thread. Allows using NSFileManager and only searches once. 

git-svn-id: 765db44a9620ed55f4f8addfd3c14fe8cd57f6bb@3299 0fceea05-a30d-0410-8a8b-80ef821fb0a1

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