* When cloning the ref data, copy the NSBitmapImageRep instead of retaining it

* Added SetNSBitmapImageRep so that wxMemoryDC can update the contents by
  replacing the entire NSBitmapImageRep.
* Added ability to create bitmaps from width/height


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@22704 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/cocoa/bitmap.h

@@ -144,6 +144,7 @@ public:
 
     // wxCocoa
     WX_NSBitmapImageRep GetNSBitmapImageRep();
+    void SetNSBitmapImageRep(WX_NSBitmapImageRep bitmapImageRep);
 
     static void InitStandardHandlers() { }
     static void CleanUpHandlers() { }