stdlib/: used by everthing

ocamlcairo/: used by codemap/codegraph, core graphics library.
ocamlgtk/:   used by codemap/codegraph, mostly for interactive menus and basic
 UI chrome.

ocamlgraph/: used by commons/graph.ml and so graph_code, also a bit by
 lang_html/? TODO why dependencies to codegraph is now shown in cg?

javalib/: used by lang_bytecode/
ocamlzip/: used by externals/javalib (used itself by lang_bytecode/)
extlib/: used by externals/javalib (used itself by lang_bytecode/)
ptrees/: used by javalib/ (TODO: deps not in codegraph because functor)

bddbddb/: used by codequery -datalog (actually not ocaml code!)
swiprolog/: used by codequery (also not ocaml code)