It is now the same as test `Draw_component`.

Advantages: no need to provide the JSON file on the command line;
single loop on nodes.

Keep trajectory lists inside dictionaries, indexed by trajectory
number, instead of lists. This way, we can keep the trajectory numbers
when we work on part of the graph, for example in a component.

Useless since commit d95e4619.

Useless since at least commit bff41cdd.

Useless since commit 8e6ce479.

The motivation is to be able to create the files `*traj*.json` for
only a component of the graph, so that `plot_traj.py` can plot the
trajectories in a single component, with different colors for
different trajectories.

The inpuy file has been re-created after commit 62ac3c9b.

To function `plot_single_traj`.

To function `plot_single_traj`.

Instead of storing it in the repository.

This should have been removed in commit 311c0598.

Remove timings from inside function `create_traj_list`.

Move function `create_traj_list` to a separate file.

Preparing for an independent script.

This should have been changed in commit 122b78b6.

Not worth it any longer. The function was introduced in commit
480800c9, when it had more to do.

Separate the construction of `traj_vert_ind` and the definition of
`traj_prop`. The motivation is to be able to create the files
`*traj*.json` for only a component of the graph, so that
`plot_traj.py` can plot the trajectories in a single component, with
different colors for different trajectories. A side benefit is that
the script `trajectories.py` becomes clearer. I have measured on the
global graph for 1993-2023 that this modification does not make a
significant change on the running time of the script.

This is useful to go from vertex to trajectory. For example, Artemis
wants to find the duration of the trajectory before each merging.

This was not useful since we do not need an array of snapshots in
`inst_eddies`. It is clearer without the integration in a snapshot
variable. The integration in a snapshot variable came from initial
commit, when there was only one program for detection of instantaneous
eddies and overlapping.

Ask for option `-assume noold_maxminloc` of Intel compiler. Without
this option, in procedure `set_max_speed`, if the speed values of all
the contours are NaN then the compiler wrongly sets `i` to 1 instead
of 0 at line 142, so `max_speed` is set to NaN instead of
`missing_speed` and the speed contour is wrong.

Replace argument `s` of `write_snapshot` by its component `list`.

Replace argument `s` of `set_all_extr` by its components. The idea is
to remove the structure `snapshot` from program `inst_edddies`.