update to 0.85.0
    
    - adjust license, as upstream changed it to MIT
    - update make-git-snapshot.sh to current locations and scheme
    - drop common package, not needed anymore
    - compositor is now in a separate package, hence reduce BuildRequires to what
      is actually needed (a lot less) and adjust summary
    - make usage of a git checkout in spec file optional
    - a %{?_isa} to requires where it makes sense