[dev-context] \xfrac and \xxfrac

Hi Hans, the commands \xfrac and \xxfrac don’t work because the use the undefined command \math_frac_alternative. \unexpanded\def\xfrac {\begingroup\let\xfrac\xxfrac\math_frac_alternative\scriptstyle} \unexpanded\def\xxfrac{\begingroup \math_frac_alternative\scriptscriptstyle} %% begin example \starttext \startformula \frac{1}{2} \quad \xfrac{1}{2} \quad \xxfrac{1}{2} \stopformula \stoptext %% end example Wolfgang