Move serialisation of pseudorects into separate functions

Keeps the code clearer.
diff --git a/common/rfb/SMsgWriter.h b/common/rfb/SMsgWriter.h
index a39cc4f..01141af 100644
--- a/common/rfb/SMsgWriter.h
+++ b/common/rfb/SMsgWriter.h
@@ -164,6 +164,12 @@
     void writePseudoRects();
     void writeNoDataRects();
 
+    void writeSetDesktopSizeRect(int width, int height);
+    void writeExtendedDesktopSizeRect(rdr::U16 reason, rdr::U16 result,
+                                      int fb_width, int fb_height,
+                                      const ScreenSet& layout);
+    void writeSetDesktopNameRect(const char *name);
+
     ConnParams* cp;
     rdr::OutStream* os;