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/ZRLEEncoder.h b/common/rfb/ZRLEEncoder.h
index e3517c1..acc6d36 100644
--- a/common/rfb/ZRLEEncoder.h
+++ b/common/rfb/ZRLEEncoder.h
@@ -28,7 +28,7 @@
   public:
     ZRLEEncoder(SMsgWriter* writer);
     virtual ~ZRLEEncoder();
-    virtual bool writeRect(const Rect& r, TransImageGetter* ig, Rect* actual);
+    virtual void writeRect(const Rect& r, TransImageGetter* ig);
   private:
     SMsgWriter* writer;
     rdr::ZlibOutStream zos;