more careful handling of Dialog_Result, with active area and color feedback;
more formal type Command.Results;
propagate command results to output, which is required to resolve update of dialog state;
clarified Markup.message: retain uninterpreted messages;
src/Pure
src/FOL
src/HOL
src/ZF
src/CCL
src/CTT
src/Cube
src/FOLP
src/LCF
src/Sequents
src/Doc