- create message-help.pd, namecanvas-help.pd and all_about_messages which
  include [namecanvas] and the additional/pd-msg docs

- check pddplinks to manuals folder (e.g., in all_about_getting_help.pd)

- improve glossary

- finish all_about_externals.pd

- finish all_about_libraries.pd

- update PDDP guidelines (or remove it)