* apt-pkg/deb/dpkgpm.cc:

* apt-pkg/deb/dpkgpm.cc:
  - fix backgrounding when dpkg runs (closes: #486222)
* cmdline/apt-mark:
  - show error on incorrect aguments (LP: #517917), thanks to
    Torsten Spindler
* cmdline/apt-get.cc:
  - if apt-get source foo=version or foo/distro can not be found,
    error out (LP: #502641)
* apt-pkg/packagemanager.cc:
  - better debug output
* doc/examples/configure-index:
  - add missing Debug::pkgPackageManager option