* Each group object now has a unique associated buffer, and vice

* Each group object now has a unique associated buffer, and vice
  versa.  This allows low-level group operations to access
  buffer-local variables associated with the group, such as
  `tab-width'.  New procedures: `group-buffer', `mark-buffer', and
  `group-tab-width'.

* Handling of `truncate-lines' and `tab-width' buffer-local variables
  is fixed.

* Extensive rewriting of redisplay, screen, and image code to squeeze
  a little more performance from it.

* Eliminate truncating buffer output ports, because they were unused,
  and depended on a feature that is no longer viable.

* Code to read files into buffers is redesigned.  Previously it read
  the file into a string, and then inserted the string into the
  buffer.  Now it reads the file directly into the buffer.

* Fix representation of characters in the range 200 to 377 octal.
  Their images are now four-character octal sequences; previously the
  images were the characters themselves.