libtorc-core: Use QHostAddress in TorcNetworkService and TorcWebSocket

- this simplifies the code and works around various edge case bugs
(mostly with IPv6) that Qt handles.
libtorc-core: Extend TorcNetwork::IPAddressToLiteral
libtorc-core: Add Torc::NetworkHostNamesChanged
libtorc-core: Notify host name in TorcBonjour when services go away.
libtorc-core: Track known host names in TorcNetwork
libtorc-core: Update known local host names from TorcNetworkedContext

(via TorcBonjour)
libtorc-core: Add cross-origin access control in TorcHTTPServer