Added new stub primitive count_attachments().

  This primitive calls CMessage::attachments(), which is unimplemented
 and returns an empty vector for the moment.

  TODO: Populate the vector with the attachments we find in the
 message.

  Updates issue #45.
  Added comment to the attachments() function.
  Correct parse attachment filenames.

  This updates issue #45
  Draw attachment names when viewing the message.

  This updates issue #45.
  save_attachment primitive mostly implemented.

  This function will write out the *ENCODED* message attachment.

  TODO: Decode appropriately using libmimetic.

  This updates issue #45.
  Saving attachments works.

  Previously we saved the "raw" attachment, now we save the decoded
 attachment as the user would expect.

  This updates issue #45.
  We don't need to archive press-mentions here.
  Removed the send_mail example.
  Removed the "TODO" comment.  This is tracked elsewhere.
  The new lua-primitive "dump_stack()" is available.

  This is only compiled into debug-builds.
  dump_stack is always available.

  This is less confusing; the difference is that the function
 is explicitly a NOP if you're not running a debug-build.
  New primitive: attachments().

  Return a table of attachment names.