Use icons set with SetImages() in Mac wxNotebook implementation

Use GetBitmapBundle(), via a helper GetPageBitmapBundle() function which
is going to be useful elsewhere too, rather than GetImageList(), as the
latter only works if the images were set using SetImageList(), while the
new version does the right thing both in this case and when the images
were set using SetImages().

include/wx/bookctrl.h

@@ -229,6 +229,15 @@ public:
     // returns true if the platform should explicitly apply a theme border
     virtual bool CanApplyThemeBorder() const wxOVERRIDE { return false; }
 
+
+    // Implementation only from now on.
+
+    // Returns an empty bundle if no image is specified for this page.
+    wxBitmapBundle GetPageBitmapBundle(size_t n) const
+    {
+        return GetBitmapBundle(GetPageImage(n));
+    }
+
 protected:
     // flags for DoSetSelection()
     enum

src/osx/cocoa/notebook.mm

@@ -22,7 +22,7 @@
 #endif
 
 #include "wx/string.h"
-#include "wx/imaglist.h"
+#include "wx/private/bmpbndl.h"
 #include "wx/osx/private.h"
 
 //
@@ -266,13 +266,11 @@ public:
             [item setView:page->GetHandle() ];
             wxCFStringRef cf( page->GetLabel() , notebook.GetFont().GetEncoding() );
             [item setLabel:cf.AsNSString()];
-            if ( notebook.GetImageList() && notebook.GetPageImage(i) >= 0 )
+
+            const wxBitmapBundle bitmap = notebook.GetPageBitmapBundle(i);
+            if ( bitmap.IsOk() )
             {
-                const wxBitmap bmap = notebook.GetImageList()->GetBitmap( notebook.GetPageImage( i ) ) ;
-                if ( bmap.IsOk() )
-                {
-                    [(WXCTabViewImageItem*) item setImage: bmap.GetNSImage()];
-                }
+                [(WXCTabViewImageItem*) item setImage: wxOSXGetImageFromBundle(bitmap)];
             }
         }
     }