[plt-scheme] 205.4

The exp-tagged code in CVS for MzScheme and MrEd is now version 205.4.

 WARNING: the editor binary format has changed again. As a result,
 non-text files saved in DrScheme 205.4 cannot be opened by previous
 versions of DrScheme. However, DrScheme 205.4 can open files saved
 by previous versions.

The changes mainly support anti-aliased 'symbol characters in X:

 * Added `size-in-pixels' support to style<%> and style-delta%.

 * X with fontconfig/Xft: Added remapping for the 'symbol family to
   match Adobe symbols (like Mac OS X). For example, when using a
   'symbol family font, "l" draws using the Unicode value for lambda,
   and "a" uses th Unicode value for alpha.

 * X with fontconfig/Xft: Added substitution support via
   comma-separated font names. (This turns out to be necessary because
   the standard freetype symbol font doesn't include symbols that are
   included in other fonts.)

 * X with fontconfig/Xft: Changed default 'symbol face mapping
   to " Standard Symbols L,Nimbus Sans L".

 * post-script-dc%'s `draw-bitmap' now uses a mask when supplied.

Matthew