It is not easy to get some work done while there is a private pool nearby, but I managed to get some things done. I have added the syntactic rules that make sure that an end-tag ends a line-comment. This involved another rule that recognizes nothing as a constructor. The follow-restrictions are really important in this case, but I think I managed to get them right.
I have also added the right syntax for backticks. This syntax is quit similar to the syntax for double-quoted strings. So the productions that make up the double-quoted strings could be reused to make the syntax for backticks.