Binding formatting items visibility to editable property. Closes #17

Author: Dansoftowner

src/main/java/com/dansoftware/mdeditor/Toolbar.java

@@ -84,6 +84,7 @@ public void changed(ObservableValue<? extends Skin<?>> observable, Skin<?> oldVa
                     }
                 }
             });
+            button.visibleProperty().bind(control.editableProperty());
             button.setId(id);
             button.setOnAction(e -> formatText(pattern));
             return button;