Fixes #73: PDF backend moves rules after comments following them.

The problem was in parsing and caused by some odd ordering in how
JavaCC executes commands for special tokens such as comments.

Fixed by sorting all items in a module by their end position.
This ensures that comments between items end up between those
two items but that comments within an item are put before the item.
Merge branch 'master' of github.com:kframework/k
Work on pdmc
Merge branch 'master' of https://github.com/kframework/k
Work on using gappa