v2.0.10: Fix #18

Fixes issue #18 - crash with malformed HELO command.
Autoupdate URL no longer pointing at Codeplex.
Prevent process crash if unhandled exception in connection thread.

Version 2 of smtp4dev (the Windows Desktop only version) has been forked by @smorks and continues to receive some maintenance. Check it out here:
https://github.com/smorks/smtp4dev