Bug#612341: libjpeg-turbo packaging (as done for Ubuntu)

[Matthias Klose <doko@ubuntu.com>]

just a note for the packaging as done in Ubuntu during the precise release
cycle. goals were

 - be able to revert the change and use libjpeg8 again if needed,
   so I did use different binary package names for the libjpeg-turbo
   sources.

 - identify packages which do use symbols found in -turbo,
   but not in libjpeg8 (using some scary symbols file processing)

 - not to touch the libjpeg8 source package (it is now removed
   in Ubuntu). Dependency packages are built from the new
   libjpeg8-empty source package.

I think that Debian wants to be able to install either libjpeg8 or
libjpeg8-turbo, so instead of the "Breaks" in the libjpeg-turbo binary packages,
the conflicting files should be handled by diversions.

  Matthias