fix move lesson

python/educational-core/src/com/jetbrains/edu/coursecreator/handlers/CCLessonMoveHandlerDelegate.java

@@ -109,7 +109,7 @@ public class CCLessonMoveHandlerDelegate extends MoveHandlerDelegate {
                                  newItemIndex - 1, EduNames.LESSON, 1);
 
     sourceLesson.setIndex(newItemIndex);
-    Collections.sort(course.getLessons(), EduUtils.INDEX_COMPARATOR);
+    Collections.sort(course.getLessons(true), EduUtils.INDEX_COMPARATOR);
     ApplicationManager.getApplication().runWriteAction(new Runnable() {
       @Override
       public void run() {

python/educational-core/src/com/jetbrains/edu/learning/StudyProjectComponent.java

@@ -162,7 +162,7 @@ public class StudyProjectComponent implements ProjectComponent {
     final ArrayList<Lesson> updatedLessons = new ArrayList<>();
 
     int lessonIndex = 0;
-    for (Lesson lesson : course.getLessons()) {
+    for (Lesson lesson : course.getLessons(true)) {
       lessonIndex += 1;
       Lesson studentLesson = currentCourse.getLesson(lesson.getId());
       final String lessonDirName = EduNames.LESSON + String.valueOf(lessonIndex);

python/educational-core/src/com/jetbrains/edu/learning/courseFormat/Course.java

@@ -48,8 +48,8 @@ public class Course {
     return getLessons(false);
   }
 
-  public List<Lesson> getLessons(boolean withAadditional) {
-    return withAadditional ? lessons
+  public List<Lesson> getLessons(boolean withAdditional) {
+    return withAdditional ? lessons
            : lessons.stream().filter(lesson -> !EduNames.PYCHARM_ADDITIONAL.equals(lesson.getName())).collect(Collectors.toList());
   }
 

python/educational-core/src/com/jetbrains/edu/learning/navigation/StudyNavigator.java

@@ -64,11 +64,7 @@ public class StudyNavigator {
     if (nextLessonIndex >= lessons.size()) {
       return null;
     }
-    final Lesson nextLesson = lessons.get(nextLessonIndex);
-    if (EduNames.PYCHARM_ADDITIONAL.equals(nextLesson.getName())) {
-      return null;
-    }
-    return nextLesson;
+    return lessons.get(nextLessonIndex);
   }
 
   public static Lesson previousLesson(@NotNull final Lesson lesson) {