Striptls

* minor fix detecting xmpp starttls tags
* dynamic creation of temporary self-signed certificate for interception (requires pyOpenSSL)

- added generic ssl/tls detection and interception
- minor changes to logging
- added GENERIC.Intercept, GENERIC.InboundIntercept, SMTP.InboundStarttlsProxy

- improves socket handling
- nonblocking ssl read/write mode to prevent striptls from stalling with large ssl payloads (e.g. large mail attachments)
- improves errorhandling
- adds SMTP.InboundStarttlsProxy, SMTP.InjectCommand, IMAP.DowngradeToV2
- fixes witnesses
- adds IRC and ACAP protocol support
- log ssl context (cipher/version)

- fixed transparent forwarding bug for unhandled protocols
- verified IMAP, POP3, NNTP, FTP, XMPP
- added SMTP.ProtocolDowngradeStripExtendedMode
- added POP3.StripFromCapabilities
- added XMPP.StripInboundTLS, XMPP.UntrustedIntercept
- added vulnerability checks

initial release
- audit mode
- vectors for SMTP, IMAP, POP3, NNTP, FTP, XMPP
- vector types: StripFromCapabilities, StripWithInvalidResponseCode, UntrustedIntercept, StripWithTemporaryError, StripWithError