Metalinks Code

fixed IE proxy grabbing bug for non-windows platforms

some minor bugfixes

added bitrate/pause/cancel capability, based on file download average, this should probably be changed to a moving average in the future

Improved merge script to handle try/except cases and not double import

Checker code now uses threading which should speed up checks significantly, minor bugfixes

Converted code to use metalink objects and expat for XML for better performance and cleaner code

Added support for using Windows proxy settings, feature 1972561.

Added capability to get bitrate for a file

major rewrite of download processes to allow for canceling and standard API between download types.

added support for proxy environment variables