Revert "Changed to ControlU to undo and to ControlR to redo in the TextField."

This reverts commit ea9eab881ce9e8a4fe3ddf9017ea6ddbe2335a92.

Terminal.Gui/Views/TextField.cs

@@ -401,7 +401,7 @@ namespace Terminal.Gui {
 				break;
 
 			// Undo
-			case Key.ControlU:
+			case Key.ControlZ:
 				if (ReadOnly)
 					return true;
 
@@ -417,7 +417,7 @@ namespace Terminal.Gui {
 				break;
 
 			//Redo
-			case Key.ControlR: // Control-y, yank
+			case Key.ControlY: // Control-y, yank
 				if (ReadOnly)
 					return true;