Merge remote branch 'twerner/show-new' into merge

* twerner/show-new:
  examine-package: lock access to printed_copyrights
  show-new: multithreading support
  show-new: no longer fiddle with sys.stdout
  examine_package: make most functions functional
  examine-package: really support option -H
  examine-package: add missing newlines to output
  examine-package: make foldable_output functional()
  examine-package: make headline() functional
  call check_deb() with correct arguments
  Add config for volatile

Signed-off-by: Joerg Jaspert <joerg@debian.org>