C++11: N2672 Initializer lists

- Modified code to use the more compact and readable initializer lists.

src/columns/ColDue.cpp

@@ -43,7 +43,7 @@ ColumnDue::ColumnDue ()
 
   Date now;
   now += 125;
-  _examples.push_back (Duration (now - Date ()).formatCompact ());
+  _examples = {Duration (now - Date ()).formatCompact ()};
 }
 
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