Doc: mention the new rdbgui4sasa opam package

Build: split the sasa opma package to separate it fron rdbgui4sasa (and remove a dependancy on gtk3)

also, start the first step at 0  instead of 1. Otherwise, with -cd, we
get more  steps than  moves. Indeed,  the first step  is not  really a
step; it just contain the initial state values.

and remove the useless node_modules directory

+  oracle enhancements in test/coloring

that is now genarated all the times by rdbg

- the mean degree was wrong
- the er generation was wrong