Initial python3 changes

Mostly just updating libraries, removing string encoding/decoding,
fixing some edge cases. No new functionality was added in this
commit.

lib/bencode/__init__.py

@@ -0,0 +1,4 @@
+"""We import some functions here, so they are available on the package level"""
+from .bencode import decode, encode  # noqa
+from .torrent import decode_torrent, encode_torrent  # noqa
+from .transform import be_to_str, str_to_be  # noqa