wt1.1b exercise description, bug fixing + custom exercise fix

lib/bloc/menu/menu_bloc.dart

@@ -26,6 +26,10 @@ class MenuBloc extends Bloc<MenuEvent, MenuState> {
         yield MenuLoading();
         await menuTreeRepository.createTree();
         yield MenuReady();
+      } else if (event is MenuRecreateTree) {
+        // ie. at language changes
+        await menuTreeRepository.createTree();
+        yield MenuReady();
       } else if (event is MenuTreeDown) {
         // get child menus or exercises
         yield MenuLoading();

lib/bloc/menu/menu_event.dart

@@ -39,3 +39,7 @@ class MenuClickExercise extends MenuEvent {
   List<Object> get props => [exerciseTypeId];
 }
 
+class MenuRecreateTree extends MenuEvent {
+  const MenuRecreateTree();
+}
+