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/common/rfb/CMsgReader.cxx b/common/rfb/CMsgReader.cxx
index 3ce7473..17152ab 100644
--- a/common/rfb/CMsgReader.cxx
+++ b/common/rfb/CMsgReader.cxx
@@ -43,13 +43,10 @@
 {
   int width = is->readU16();
   int height = is->readU16();
-  handler->setDesktopSize(width, height);
   PixelFormat pf;
   pf.read(is);
-  handler->setPixelFormat(pf);
   CharArray name(is->readString());
-  handler->setName(name.buf);
-  handler->serverInit();
+  handler->serverInit(width, height, pf, name.buf);
 }
 
 void CMsgReader::readMsg()