libtorc-core: Fix WebSocket creation from client peers

- fix return value from TorcNetworkedContext::event
- actually add the new peer to the list of known peers
- make UpgradeSocket static for consistency with TorcHTTPServer
libtorc-core: Start adding WebSocket sub-protocol support
libtorc-core: Don't send OpClose if handshake isn't complete
libtorc-core: Add TorcWebSocket::SubProtocolsFromPrioritisedString