23c: remove last unicode literals
23c: remove last unicode literals

These are special: they're supposed to check the Python representation
of unicode strings.  In fact the representation is not checked; what's
checked is that when the representation is evaluated it matches the
desired value.  So we just try to get close, and eliminate the unicode
literal syntax.

CantemoInternal/pyxb,CantemoInternal/pyxb,pabigot/pyxb,pabigot/pyxb,CantemoInternal/pyxb