o Ignore all text after ' # ' (doesn't conflict with option flag)
o Command aliases
o Add user-defined setions
o Add a SOURCE section with link to git repo
o Bullet-lists
o Allow a USAGE section (and NAME)
o Find source in code an adjust line number in error messages 
o Rename line and char to lineno and charno
o Client-defined argument types
o Rename Expr -> ?
o Find clean(er) procedural object model
o Allow assignment to options (this makes practical stuff easier)
o Special handling of --help arguments so that '--help command' is possible
o Support for paging of help:
    begin 
      file = Tempfile.new("prick") 
      file.puts HELP.split("\n").map { |l| l.sub(/^  /, "") } 
      file.flush 
      system "less #{file.path}" 
    ensure 
      file.close 
    end 

+ Bold text output
+ Recursive format of commands
+ Rename Compiler -> Interpreter


OLD

o Fix that it is near unsable when the user doesn't do 'include ShellOpts'
o Subcommands can be parsed as well: 
    opts, args = Shellopts.process(OPTIONS, ARGV)
    ...
    opts, command = opts.process
    case command
      when ...
    end
o 'help' should list commands in declaration order
o 'help' should use all levels by default
o 'help' should always include top-level options (try setting levels: 10 and
  see top-level options are gone
o A ShellOpts#shift command that makes it possible for Array#expect to emit
  relevant error messages

+ Somehow escape comments where a line starts with an option name
+ Parse and check enumeration arguments ('--debug=tokens|ast|idr|...')