Use vector instead of array of wxDataFormats

Also rename EnableDropTarget() to EnableDropTargets(), as calling
EnableDropTarget(wxDF_XXX) would be ambiguous due to the existence of a
non-explicit wxVector ctor taking size_t (which is a mistake on its own,
but is probably not worth changing any more).

include/wx/qt/dataview.h

@@ -119,7 +119,7 @@ public:
     virtual bool IsExpanded( const wxDataViewItem & item ) const;
 
     virtual bool EnableDragSource( const wxDataFormat &format );
-    virtual bool DoEnableDropTarget( const wxDataFormatArray& formats ) wxOVERRIDE;
+    virtual bool DoEnableDropTarget( const wxVector<wxDataFormat>& formats );
 
     static wxVisualAttributes
     GetClassDefaultAttributes(wxWindowVariant variant = wxWINDOW_VARIANT_NORMAL);