General

Added some tests to improve overall code coverage.
The UW client identifier is now recognised as uTorrentWeb.
A list of peers are retained when a torrent is stopped and restarted. This will allow connections to be initiated before the first announce completes. It can be useful when the tracker is unreliable. Peers which are retained are replaced with fresh peers as soon as a tracker, or DHT, announce completes. This ensures the freshest set of peers is always used when initiating connections.
Improved performance of reading/writing files. Patch thanks to @ilyalatt .
Misc code formatting for consistency.

Provide feedback