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

Of course this is only useful for algo that compute some kind of trees (more
specifically, this only work if the state contains a variable named "par" !)

Moreover, it was not taking into account whether the graph was directed or not.