* install.txt: force ocaml 4.01.0
* configure: ask for ocaml 4.01
* lang_ml/analyze/typed_ml: new format in 4.01
* lang_ml/analyze/meta_ast_cmt.ml: refresh with 4.01
* lang_ml/analyze/graph_code_cmt.ml: part1 to cope with changes in AST in 4.01