added parameter validation for __contains__ run on empty dictionary
simplified contains - removed premature optimization
bytearray.decode and byte.decode can distinguish between None and missing arg
socket send, sendall and sendto accept bytes as argument
Merge pull request #223 from paweljasinski/cp35543

socket send, sendall and sendto accept bytes as argument
Merge pull request #222 from paweljasinski/cp35544

bytearray.decode and byte.decode can distinguish between None and missin...
Merge pull request #221 from paweljasinski/cp35348

fixed cp35348