[NTG-context] some minor problems (mkiv)

hi, i'm still trying to make my code run with mkiv. here are two minor problems. the first one is easy to deal with, but the second one currently breaks my testbed. % engine=luatex \setupcolors[state=start] \starttext \startMPcode label("no color",origin) withcolor red; % always black \stopMPcode \string{\{} \stoptext greetings, peter