Metalinks Code

- Code cleanup
- FTP close connection speed improvement
- Added documentation for how to use as a library
- Sort by country pref first (if set), then pref value in metalink
- reworked code to better handle URLs by creating a class

Updated test cases

Added test cases and script

- segmented download FTP size support
- support for user specified OS and language preferences
- finished FTP proxy support

# Version 3.3
# -----------
# - Bugfix for when type attr not present
# - Support for FTP segmented downloads

added origin support, todo list

Revived segmented FTP development, still needs some bugs worked out of it

Now handles all SHA hash types and MD5

minor tweaks and bugfixes from pychecker

# Version 3.0
# -----------
# - Speed and bandwidth improvements for checking mode
# - Added checking of chunk checksums
# - If chunk checksums are present, downloads are resumed
# - Proxy support (experimental, HTTP should work, FTP and HTTPS not likely)