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/osx/dataview.h

@@ -209,7 +209,7 @@ public:
   virtual void EditItem(const wxDataViewItem& item, const wxDataViewColumn *column) wxOVERRIDE;
 
 #if wxUSE_DRAG_AND_DROP
-  virtual bool DoEnableDropTarget( const wxDataFormatArray& formats ) wxOVERRIDE;
+  virtual bool DoEnableDropTarget( const wxVector<wxDataFormat>& formats ) wxOVERRIDE;
 #endif // wxUSE_DRAG_AND_DROP
 
  // returns the n-th pointer to a column;