Torf

- Don't leave an empty file when calling write() on an invalid torrent

- Major rewrite with lots of tests that should fix the most obvious bugs
- The options --source and --nosource have been removed
- The option --nocreator has been added
- Output is now easier to parse when stdout is not a TTY (e.g. when piping to
grep, cut, awk, etc)

Final release

- Fixed a bug where overwriting a torrent file resulted in corrupt torrent
- Added property 'pieces' that returns the number of pieces
- Added property 'filetree' that can be used to create a beautiful tree of a
torrent's content
- Added property 'is_ready' that is True when torrent can be exported
- When reading torrent files, don't read large files all the way to EOF before
failing
- All exceptions now have an 'errno' attribute (see 'errno' module)

- Torrent.write() and Torrent.read() take a file path instead of an opened
file object
- Some exception names have changed
- Allow reading arbitrary bencoded data with validation turned off
- Default 'created_by' value is now 'torf/<version>'

- Reduce entropy with 'randomize_infohash' enabled (some parsers seem to have
issues with large integers)