Add support for character encodings

Previous commit added support of it to Csocket.
When encoding is specified, core will convert incoming messages to UTF-8,
and outgoing messages from UTF-8.
When no encoding is specified, it will do nothing to bytes, like before.
This is to be changed somewhere in future, to have UTF-8 on wire by
default too.
When encoding's name starts with *, incoming messages will be treated as
UTF-8, if it is already correct UTF-8. Otherwise, it's converted.

Fix #151
Fix #366

src/Client.cpp

@@ -673,6 +673,7 @@ void CClient::AcceptLogin(CUser& User) {
 	SetTimeout(540, TMO_READ);
 
 	SetSockName("USR::" + m_pUser->GetUserName());
+	SetEncoding(m_pUser->GetClientEncoding());
 
 	if (!m_sNetwork.empty()) {
 		m_pNetwork = m_pUser->FindNetwork(m_sNetwork);