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/RawEncoder.cxx b/common/rfb/RawEncoder.cxx
index 4b8de6b..b4e38db 100644
--- a/common/rfb/RawEncoder.cxx
+++ b/common/rfb/RawEncoder.cxx
@@ -31,7 +31,7 @@
 {
 }
 
-bool RawEncoder::writeRect(const Rect& r, TransImageGetter* ig, Rect* actual)
+void RawEncoder::writeRect(const Rect& r, TransImageGetter* ig)
 {
   int x = r.tl.x;
   int y = r.tl.y;
@@ -50,5 +50,4 @@
     y += nRows;
   }
   writer->endRect();
-  return true;
 }