We are more clearly separating opening files and reading from them.

This is no longer needed since commit d16d3f1c.

Use `e_overestim.txt` instead of `node_id_param.json`. Since commit
43d2eff6, we wrote only `e_overestim` to the JSon file. Simpler to
write the value alone in a text file.

Option should have been updated in commit e35226da.

Bad names from commit c45cd728.

Following renaming of script.

Add script converting Graph-tool output to edgelist. So we can use
analysis scripts developed in Overlap on results of trajectory scripts.

Move tests on trajectories to new test file `Trajectories/tests.json`.

Directory Tests was created in commit 40a1c5aa.

Rewrite following an idea of R\'emi Laxenaire: loop on edges in order of
ascending cost function.

Rename trajectories to `traj_segm` and `expanded_trajectories` to
`expanded_traj`.

No need for this property to be internal.

Instead of a global variable with hidden modification in a method of Visitor.

So that segments in a trajectory are in chronological order.