Add OnSendToIRCMessage and OnSendToClientMessage

This also alters PutClient such that the CMessage variant handles
sending messages, rather than the CString variant. As a side bonus, this
gives callers better information on whether the message was sent to the
client. Additionally, it eliminates the need for a hook to let modules
set the tags sent to a client, as that can now be done inside
OnSendToClientMessage.

modules/modpython/znc.py

@@ -655,6 +655,12 @@ class Module:
     def OnUnknownUserRawMessage(self, msg):
         pass
 
+    def OnSendToClientMessage(self, msg):
+        pass
+
+    def OnSendToIRCMessage(self, msg):
+        pass
+
 
 def make_inherit(cl, parent, attr):
     def make_caller(parent, name, attr):