Release v0.9.6.

- Conversations (email threading) are now supported.
- Now only requires .NET 4.0 Client Profile, down from .NET 4.0.
- Emails with a sent date from previous years now correctly show the
full date in a toast.
- Fixed a crash when an email was received that contained invalid
characters in the To field.
- The login window is now displayed when an error or disconnection
occurs.
- Toasts now display the user part of the sender's email address if
there is no display name.
- Toasts now properly reset upon reconnecting.