move keeping track of the chunk to unpack routine
make sure that the checksum is checked OUTSIDE the sink
fix indentation
yay, debug messages when decompressing in correct order again
factor out progress reporting to unpack
double pretty printing when using debug on decompression
clean up imports
fix white lines
argl, failed to reset file pointers before compare
fix PlainMemorySink to actually decompress, my bad
make sure to do some type checking on the objects

I know it's not exactly the Python way... But ABC
no need to __call__ the source
a simple __iter__ is enough for the sources
shift a comment to the correct place
Merge branch 'enhance/sink_source'

* enhance/sink_source:
  shift a comment to the correct place
  a simple __iter__ is enough for the sources
  no need to __call__ the source
  make sure to do some type checking on the objects
  fix PlainMemorySink to actually decompress, my bad
  argl, failed to reset file pointers before compare
  fix white lines
  clean up imports
  double pretty printing when using debug on decompression
  factor out progress reporting to unpack
  yay, debug messages when decompressing in correct order again
  fix indentation
  make sure that the checksum is checked OUTSIDE the sink
  move keeping track of the chunk to unpack routine
update the changelog