Remove wxOSX/Carbon support.

Cocoa has been the default toolkit in wxWidgets for a long time. There is really no good reason to use Carbon in 2016 and this removes a lot of unused and unmaintained code.

interface/wx/dataview.h

@@ -182,9 +182,6 @@ public:
         @return
             @true if this item should be enabled, @false otherwise.
 
-        @note Currently disabling items is not supported by the wxOSX/Carbon
-              implementation.
-
         @since 2.9.2
     */
     virtual bool IsEnabled(const wxDataViewItem &item,
@@ -1274,8 +1271,6 @@ public:
 
         Doesn't do anything if the item or this column is not editable.
 
-        @note Currently not implemented in wxOSX/Carbon.
-
         @since 2.9.4
     */
     virtual void EditItem(const wxDataViewItem& item, const wxDataViewColumn *column);