[plt-scheme] 204.4 addition

Although the exp-tagged code in CVS is still labelled as version 204.4,
I've just tagged a significant change for some X users.

MrEd now supports anti-aliased fonts via FreeType/fontconfig/Xft, at
least when supported by the X server and by compile-time libraries. The
new --disable-xft flag for `configure' disables the new font system
when `configure' would otherwise enable it.

The old X font system (without anti-aliasing) co-exists with the new
one. In particular, the old interpretation of "face" names remains, but
with a small extension: a face name that starts with a space is
interpreted as a fontconfig family name after dropping the space. This
extra-space convention is a little bit of hack, but it provides a
simple transition path, it's invisble to font-dialog users, and it
makes new font names appear before old font names in a sorted list.

When the new font system is enabled (at run time), the built-in font
mapping specifies fontconfig fonts:

 (|MrEd:ScreenSystem__| " Sans")
 (|MrEd:ScreenDefault__| " Sans")
 (|MrEd:ScreenModern__| " Monospace")
 (|MrEd:ScreenRoman__| " Serif")
 (|MrEd:ScreenDecorative__| " Nimbus Sans L")
 (|MrEd:ScreenSwiss__| " Nimbus Sans L")
 (|MrEd:ScreenScript__| " URW Chancery L") 

With fontconfig, the "Sans", "Serif", and "Monospace" names apparently
mean the system-wide default sans-serif, serif, and monospace fonts,
respectively. If anyone knows where these special family names are
documented (and what other such special names exist), please let me
know.

Finally, when the new font system is enabled, the default nominal font
size for an editor is 9pt instead of 12pt. I'm not sure about this
choice; it's merely the one that looks best to me on my machine.

Controls uses a 10pt font by default, which appears to be consistent
with other applications (e.g., Mozilla, Gnome Terminal).

Matthew