* commons/: cleaning up, remove backtrace, sexp_common, introduce console.ml
CEs
* graph_code/graph_code_class_analysis.ml: skeleton, and better test infra
* commons/concurrency.ml: misc
* h_visualization/simple_color.ml: move from commons/
* Makefile: remove deps to ocamlgraph for basiclibs!
* h_program-lang/layer_code.ml: fix circular deps