Fix markdown in thread bodies and comments.

lms/static/coffee/src/discussion/views/discussion_thread_inline_view.coffee

@@ -54,7 +54,7 @@ class @DiscussionThreadInlineView extends DiscussionContentView
 
   convertMath: ->
     element = @$(".post-body")
-    element.html DiscussionUtil.postMathJaxProcessor(element.html())
+    element.html DiscussionUtil.postMathJaxProcessor DiscussionUtil.markdownWithHighlight element.html()
     MathJax.Hub.Queue ["Typeset", MathJax.Hub, element[0]]
 
   renderResponses: ->

lms/static/coffee/src/discussion/views/discussion_thread_view.coffee

@@ -43,7 +43,7 @@ class @DiscussionThreadView extends DiscussionContentView
 
   convertMath: ->
     element = @$(".post-body")
-    element.html DiscussionUtil.postMathJaxProcessor(element.html())
+    element.html DiscussionUtil.postMathJaxProcessor DiscussionUtil.markdownWithHighlight element.html()
     MathJax.Hub.Queue ["Typeset", MathJax.Hub, element[0]]
 
   renderResponses: ->

lms/static/coffee/src/discussion/views/response_comment_view.coffee

@@ -2,6 +2,7 @@ class @ResponseCommentView extends DiscussionContentView
   tagName: "li"
   template: _.template($("#response-comment-template").html())
   initLocal: ->
+    # TODO .response-local is the parent of the comments so @$local is null, not sure what was intended here...
     @$local = @$el.find(".response-local")
     @$delegateElement = @$local
 
@@ -14,8 +15,9 @@ class @ResponseCommentView extends DiscussionContentView
     @convertMath()
     @
   convertMath: ->
-    body = @$(".response-body")
+    body = @$el.find(".response-body")
     body.html DiscussionUtil.postMathJaxProcessor DiscussionUtil.markdownWithHighlight body.html()
+    # This removes paragraphs so that comments are more compact
     body.children("p").each (index, elem) ->
       $(elem).replaceWith($(elem).html())
     MathJax.Hub.Queue ["Typeset", MathJax.Hub, body[0]]