REHASH, improved listeners and mode fixes

We now support dynamically reloading the config file, along with some new IRCv3 capabilities and some fixes.

The REHASH changes are fairly extensive here, but should now be stable (this also fixes a denial of service possible with the old code).

Security

• Prevent a denial of service where the server would stop accepting connections.

Added

• Added REHASH command.
• Added ability to message channel members with a specific privelege (i.e. support for STATUSMSG).
• Added ability to enable and disable SASL.
• Added support for IRCv3 capabilities cap-notify and echo-message.

Changed

• Server operators no longer have permissions to do everything in channels.

Fixed

• MODE: Fixed issue where channel privelege changes returned incorrectly.