eliminated pointless theory graph (reverting parts of a56eab490f4e): it caused problems with loaded vs. non-loaded node names, e.g. for theory Pure (see also 29bb1ebb188f);
src/Pure
src/FOL
src/HOL
src/ZF
src/CCL
src/CTT
src/Cube
src/FOLP
src/LCF
src/Sequents
src/Doc
src/Tools