Remove partial update functionality

Get rid of the ability of encoders to only send part of the
rectangle they are given as we don't want partial updates
anyway.
diff --git a/common/rfb/TightEncoder.h b/common/rfb/TightEncoder.h
index 3632539..a499783 100644
--- a/common/rfb/TightEncoder.h
+++ b/common/rfb/TightEncoder.h
@@ -86,7 +86,7 @@
     virtual void setQualityLevel(int level);
     virtual void setFineQualityLevel(int quality, int subsampling);
     virtual int getNumRects(const Rect &r);
-    virtual bool writeRect(const Rect& r, TransImageGetter* ig, Rect* actual);
+    virtual void writeRect(const Rect& r, TransImageGetter* ig);
 
   private:
     bool checkSolidTile(Rect& r, rdr::U32* colorPtr, bool needSameColor);