TextEditor: Flip default to 'duplicatedSupported'

opt-out now, for all editors created by BaseTextEditorFactories.

Change-Id: I01d0a9ff26320fcd0b84ff90ff22c747cf84b84c
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/cmakeprojectmanager/cmakeeditor.cpp

@@ -65,7 +65,6 @@ namespace Internal {
 
 CMakeEditor::CMakeEditor()
 {
-    setDuplicateSupported(true);
 }
 
 void CMakeEditor::finalizeInitialization()