Scripting and error handling

[Marco Gerards]

Hi,

As you might have noticed, I just committed a patch.  It fixes the
following issues:

- Cleaned up the parser code.  It was a bit messy because of the
  concatenated variables handling.  I just disabled that feature for
  now and will re-implement it in some other way.

- Empty menus will not be shown.

- No crashes when `title' is used.

- Better error handling.  If one menu entry contains a mistake, it will
  not appear in the menu, but others will.

Some things for me to work on:

- The lexer really sucks IMO.  So I am looking at flex to see if it
  can generate a good lexer for us.  It depends on some syscalls, so
  perhaps it is not possible for us to use flex...

- When a menu entry contains a typo, it should appear as disabled or
  so.  I will look into that.  So in that case you should still be
  able to edit and boot the entry after editing.

- More fine grained error handling should be added.  So error messages
  can be precise and tell the user *exactly* what the problem is.

- The parser should be made reentrant.

- And of course I should add a lot more features.  :-)

- Please tell me if something still causes problems, etc.

--
Marco