L10N

- Added an error message for missing key file.
Documentation

- Added references to new configuration settings.
Documentation

- Added new configuration settings to 'show' command and man page.
Certificates

- Implemented TLSClient::trust, which overrides certifcate validation.
Certificates

- Added certificate verification callback.
Certificates

- Stores the host name in the session, for handѕhake validation.
Certificates

- Stores the socket in the session.
Certificates

- Added feedback from GnuTLS to the handshake diagnistic message.
TLS

- Corrected ::recv error handling.
Documentation

- Added recently closed bugs to ChangeLog.
Code Cleanup

- Removed unused header.
- Added ctor initialization.
- Removed misleading comment.