#864 : add maunal test cases for undo & redo

manual-tests/org.yakindu.sct.test.manual/testcases/sct_testcase_02_editor.textile

@@ -24,4 +24,5 @@ h1(#Test2). Yakindu SCT Testcase 02 - Editor
 | 2.16.3 | Navigator View | Expand the region entry in the tree view. | The initial state and the LightOff and LightOn states are displayed as children with icons. | %{color:red}open% |
 | 2.16.4 | Navigator View | Expand the states entries in the tree view. | The outgoing transitions of the states are displayed with icon and trigger/guard. | %{color:red}open% |
 | 2.17 | View | Press *[Ctrl++]* to zoom in and *[Ctrl++]* to zoom out. | The view should zoom in and out. | %{color:red}open% |
+| 2.18 | Undo & Redo | Select a region which includes at least a state with an outgoing transition <p> Press *DEL* to delete the region <p>Undo deletion by Strg+Z <p> Redo deletion by Strg+Y <p> | The deletion should properly be undone an redone<p> The elements involved during deletion, undo and redo should be changeable after Redo | %{color:red}open% |