Putting a tab character into the name of a discussion forum will trigger a JSON syntax error response whenever the post is displayed using AJAX.

Reproduction steps:

1. Create a new discussion forum
2. Create a topic in the discussion forum with a tab character in the title (you will probably have to copy and paste it in)
3. Reply to the discussion forum with the non advanced editor (that loads via ajax)
4. A JSON parsing syntax error will be triggered when trying to parse the AJAX response

Expected Behavior:

The forum should post the response to the discussion.

Observed Behavior:

An error is thrown.

This also affects loading discussions for grading.