* apt.Package:
  - change all candidateInstalledSize() to installSize(useCandidate=True)
    same for candidateOrigin()  (see downloadable for a example). 
  - might be better to have "Package.candidate.{downloadable,size,etc}
 
* aptsources:
 - make the distro detection in sources.list more clever by using the
   origin informaton to avoid adding full uris to (unofficial/internal)
   mirrors