Add wxBitmap::CreateWithLogicalSize()

The new function has a more clear name than CreateScaled() it replaces
and uses a more useful parameter order, with the scale factor, which
must always be specified when using it, coming before, and not after,
the depth, which almost never needs to be specified and so can be left
at its default value in 99% of cases.

src/gtk/bitmap.cpp

@@ -990,9 +990,9 @@ void wxBitmap::SetMask( wxMask *mask )
 }
 
 #ifdef __WXGTK3__
-bool wxBitmap::CreateScaled(int w, int h, int depth, double scale)
+bool wxBitmap::DoCreate(const wxSize& size, double scale, int depth)
 {
-    Create(wxRound(w * scale), wxRound(h * scale), depth);
+    Create(size*scale, depth);
     M_BMPDATA->m_scaleFactor = scale;
     return true;
 }