New callback: on_reply_transform_subject()
  Fixed name of on_reply_transform_subject().
  Fixed documentation.
  New member function: get_input

  This uses the prompt() primitive.
  Use the new CLua::prompt_for() method.

  This simplifies the prompting for recipient/subject.
  Rationalized the sending + archiving of mails.

  Starting to get cleaner now; there is only a single copy
 of the code that takes a temporary file, sends it out via
 sendmail, and then archives it in ~/Maildir/Sent.

  The only issue is that suddenly our bindings_files are starting
 to become a mixture of actual bindings and supporting functions.
 Probably not a problem though?
  Shuffled code around.

  Now `src/bindings_message.cc` has the form:

    * utility methods (alphabetica)
    * primitive implementations (alphabetical).

  This is a pattern that will continue, though I believe that
 this is the only src/binding_* file which has utility methods
  Renamed ::all_messages to ::total_messages.

  This fixes the intent.
  minor reformat & comment update.
  Fixed style of the lumail.lua file.

  As caught by "make style".

  I keep wanting to terminate Lua with ";", as I do with perl.

  TODO: Add a pre-commit git-hook