deleted empty fxml and unused constant

Author: ddamke

src/main/java/de/doubleslash/keeptime/common/Resources.java

@@ -37,7 +37,7 @@ public enum RESOURCE {
       FXML_SETTINGS("/layouts/settings.fxml"),
       FXML_VIEW_POPUP_LAYOUT("/layouts/ViewLayoutPopup.fxml"),
       FXML_REPORT("/layouts/report.fxml"),
-      FXML_ABOUT("/layouts/about.fxml"),
+
       FXML_MANAGE_PROJECT("/layouts/manage-project.fxml"),
       FXML_MANAGE_WORK("/layouts/manage-work.fxml"),