White space, really
Racket: not loading errortrace by default

The new submodules and errortrace interact badly, for what i've seen.
In particular, even with the submodule[+*] loading correctly, its
namespace doesn't have all identifiers bound, and new ones seem to
appear in the bindings lists (things like a.1 or b.2, when a and b are
the actual identifiers defined inside the module).

Since moreover someone mentioned in the devel ML that errortrace is in
general terms buggy, i guess we can leave without it for the time
being.