A teacher can reply privately to forum posts

This test requires 2 teacher accounts, 2 student accounts and 5 forum activities, one of each type (standard forum, standard forum in blog-like format, each person posts one discussion, Q and A forum, single simple discussion) containing posts from the two students.

1. Log in as teacher1, go to a forum, view a discussion and add a private reply to a post by student1.
2. Try editing the private reply, then deleting it, then adding another private reply.
3. Log out then log in as student1 and view the private reply. Check that you are not able to reply to it, nor add a private reply to a post by student2.
4. Log out then log in as teacher2 and check that you are able to view the private reply for student1 but are not able to reply to it.
5. Check that the private reply permalink works as expected.
6. Check that the private reply is only visible in the discussion thread and not on the forum page.
7. Log out then log in as student2 and check that you are NOT able to view the private reply for student1.
8. Repeat the above steps for each of the 5 forum types.