Log Message:
Update to 6.21.4.  Closes PR pkg/19298 and PR pkg/21934.  Changes:

Version 6.21.4 (17 Jun 03):

* Applied patches from www.inform-fiction.org to the source and library, as
  supplied by Dave Griffith <dgriffi@cs.csubak.edu>.
* There's a new Ruins demo game, with more stuff implemented.  The previous
  Ruins demos have been renamed: ruins -> ruins1, ruinsplus -> ruins2.  The
  new one is called ruins3.
* The Alice demo in the 'tutor' directory has been updated to the latest
  Inform version.
* Included a more up-to-date inform-mode.el.

Version 6.21.3 (6 Nov 02):

* The Inform included here is now Andrew Plotkin's bi-platform version,
  which can compile for Glulx, following a suggestion by Marshall
  T. Vandegrift <vandem2.rpi.edu>.
* Now includes HTML version of the Designer's Manual.
* Several more library include files have been added.