Stop buffering and echoing CTCP requests and responses to other clients, except for /me

Fix interaction between self-message and CTCP:
CTCP request from client A gets reflected from ZNC to client B, because
B has self-message. B sees this as a usual CTCP request (from the same
nick), and replies (to the same nick). ZNC reflects that response to A
because A has self-message, and also passes that response to IRC server,
which sends that response back to ZNC, which sends it to its both clients.

Close #1488

src/Client.cpp

@@ -1021,8 +1021,6 @@ bool CClient::OnCTCPMessage(CCTCPMessage& Message) {
         }
 
         if (m_pNetwork) {
-            AddBuffer(Message);
-            EchoMessage(Message);
             PutIRC(Message.ToString(CMessage::ExcludePrefix |
                                     CMessage::ExcludeTags));
         }