[plt-dev] Default syntax printer

Is there any chance we can change the default printer to show the
syntax->datum of syntax objects?  Instead of #<syntax> in error
messages, it would be much more helpful to see something like #'(foo
x) or #<syntax:(foo x)>.  Even the error printer, which cuts off at a
certain point with "...", would be preferable to the current total
opacity.

Carl Eastlund