- The preamble and cloding line (\end{document}) are now written
  under th econtrol of tex-cenverter.rb
- The file `preamble` is still ncessary, but it contains
  only generic inormation.  There should be a default preamble
  and the option of overriiding it with a user provide file
- The file 'macros
  is where the  macro definitions go.  We should provide for this
  file being empty or not present.
- The title, author and date are mandatory and are set in the
  Asciidoc file in the usual way.