Add filename support for GZIPCompressedStream (#4)

ADDED:
 - new parameter "filename" which enables naming of the compressed stream
MODIFIED:
 - incorporated "filename" in the constructor call "gzip.GzipFile"
REMOVED:
 - nothing

gzip_stream.py

@@ -8,14 +8,16 @@
 
 
 class GZIPCompressedStream(io.RawIOBase):
- def __init__(self, stream: BinaryIO, *, compression_level: int):
+ def __init__(self, stream: BinaryIO, *, compression_level: int,
+ filename: str = None):
  assert 1 <= compression_level <= 9
 
  self._compression_level = compression_level
  self._stream = stream
 
  self._compressed_stream = io.BytesIO()
  self._compressor = gzip.GzipFile(
+ filename=filename,
  mode='wb',
  fileobj=self._compressed_stream,
  compresslevel=compression_level