Stop requiring CConnection::serverInit() to be overridden

Add an explicit callback for subclasses to do their startup in. This
makes it easier to do proper ordering, and avoids mistakes.
diff --git a/common/rfb/CConnection.cxx b/common/rfb/CConnection.cxx
index a503a2c..805c8c3 100644
--- a/common/rfb/CConnection.cxx
+++ b/common/rfb/CConnection.cxx
@@ -335,6 +335,14 @@
   CMsgHandler::setExtendedDesktopSize(reason, result, w, h, layout);
 }
 
+void CConnection::serverInit()
+{
+  state_ = RFBSTATE_NORMAL;
+  vlog.debug("initialisation done");
+
+  initDone();
+}
+
 void CConnection::readAndDecodeRect(const Rect& r, int encoding,
                                     ModifiablePixelBuffer* pb)
 {
@@ -363,10 +371,8 @@
 {
 }
 
-void CConnection::serverInit()
+void CConnection::initDone()
 {
-  state_ = RFBSTATE_NORMAL;
-  vlog.debug("initialisation done");
 }
 
 void CConnection::fence(rdr::U32 flags, unsigned len, const char data[])
diff --git a/common/rfb/CConnection.h b/common/rfb/CConnection.h
index 1e66a64..c996ecf 100644
--- a/common/rfb/CConnection.h
+++ b/common/rfb/CConnection.h
@@ -100,6 +100,8 @@
                                         int w, int h,
                                         const ScreenSet& layout);
 
+    virtual void serverInit();
+
     virtual void readAndDecodeRect(const Rect& r, int encoding,
                                    ModifiablePixelBuffer* pb);
 
@@ -113,9 +115,11 @@
     // authSuccess() is called when authentication has succeeded.
     virtual void authSuccess();
 
-    // serverInit() is called when the ServerInit message is received.  The
-    // derived class must call on to CConnection::serverInit().
-    virtual void serverInit();
+    // initDone() is called when the connection is fully established
+    // and standard messages can be sent. This is called before the
+    // initial FramebufferUpdateRequest giving a derived class the
+    // chance to modify pixel format and settings.
+    virtual void initDone();
 
 
     // Other methods