[plt-scheme] 204.1

The exp-tagged code in CVS for MzScheme and MrEd is now version 204.1.

   IMRPOTANT: The "graphical" file format has changed. Non-text files
   saved with DrScheme v204.1 will not open with v204 and earlier.
   (Expect another minor change in the near future.)

Changes:

 * Added a `new' form to (lib "class.ss"), which is like `instantiate',
   but without the by-position part (i.e., it's by-name only).

 * Added "smoothing" arguments/fields to font%, style-delta%, and
   style<%>. (This is why the "graphical" file format changed.)

 * Mac OS X, 10.2 and up: Text drawing uses Quartz smoothing by
   default, except when the font family is designated 'modern (a poor
   keyword for "fixed width") and the size is between 9 and 13.

 * Windows XP: When ClearType is turned on system-wide, 'modern text
  between 9 and 13 is drawn without ClearType by default.

 * Mac OS X: Miscellaneous improvements to screen update. in
   particular, frames and dialogs tend to appear with pre-drawn
   content, instead of appearing initially blank.

 * Changed the expansion-time information associated with a struct-type
   name to include an identifier for the super-type.

 * Added an optional argument to `system-library-subpath'.

 * 3m: changed to the calling convention for managing GC_variable_stack.

Matthew