Let CMsgHandler::serverInit() handle initial set up

Avoid using the callbacks used for runtime changes for the initial
setup. They weren't really useful anyway as you could not allocate
a framebuffer without also knowing the pixel format. So make things
more clear by letting serverInit() get the initial settings.
diff --git a/vncviewer/CConn.cxx b/vncviewer/CConn.cxx
index 23257ee..3e156ad 100644
--- a/vncviewer/CConn.cxx
+++ b/vncviewer/CConn.cxx
@@ -363,8 +363,7 @@
 void CConn::setName(const char* name)
 {
   CConnection::setName(name);
-  if (desktop)
-    desktop->setName(name);
+  desktop->setName(name);
 }
 
 // framebufferUpdateStart() is called at the beginning of an update.
@@ -495,9 +494,6 @@
 
 void CConn::resizeFramebuffer()
 {
-  if (!desktop)
-    return;
-
   if (continuousUpdates)
     writer()->writeEnableContinuousUpdates(true, 0, 0,
                                            server.width(),