removed some code smells

src/main/java/ninja/javafx/smartcsv/fx/table/EditableValidationCell.java

@@ -125,7 +125,7 @@ public class EditableValidationCell extends TableCell<CSVRow, CSVValue> {
         });
     }
 
-    private class ValueTextField extends TextField {
+    private static class ValueTextField extends TextField {
         private CSVValue value;
 
         public ValueTextField(CSVValue value) {

src/main/java/ninja/javafx/smartcsv/fx/table/ObservableMapValueFactory.java

@@ -47,7 +47,6 @@ public class ObservableMapValueFactory implements
     @Override
     public ObjectProperty<CSVValue> call(TableColumn.CellDataFeatures<CSVRow, CSVValue> features) {
         CSVRow row = features.getValue();
-        ObjectProperty<CSVValue> value = row.getColumns().get(key);
-        return value;
+        return row.getColumns().get(key);
     }
 }