clarified ML_Context.expression: it is a closed expression, not a let-declaration -- thus source positions are more accurate (amending d8849cfad60f, 162a4c2e97bc);
src/Pure
src/FOL
src/HOL
src/ZF
src/CCL
src/CTT
src/Cube
src/FOLP
src/LCF
src/Sequents
src/Doc
src/Tools