Add bracket list, remove dead code

The magic of git means I don't need that commented-out code anymore.

The bracket list is for upcoming comments/quoting work.
Add support for single-line comments

Why not use the syntax table's builtin comment handlers? It would grab
special comments (#`, #|, #=) without consideration for their
embedability, and we can't teach the syntax table to handle P6's
embedded comments. Better to do all the comment stuff ourselves.
Update test file a bit for comments.
More fixes to the testfile

Revealing a fatal flaw in our comment handling! Curses!