Remove dummy arguments nlon, nlat, corner, step of procedure
`read_snapshot`, use module variables instead. Note that we keep copy
as a dummy argument instead of using the variable of module
`config_graph_m`, because we want the procedure `read_snapshot` to be
usable outside of the `eddy_graph` program.

Remove dummy arguments nlon, nlat, periodic, `dist_lim` of
procedure `overlap`, use module variables instead.

Changing my mind. In an SHPC, store shapefiles in
"Slice_{slice}/{orientation}" instead of
"{orientation}/Slice_{slice}". Two reasons: easier to store accessory
files from running `inst_eddies`, such as `perf_report` and output
from Torque submission script; clearer that a slice should contain the
same dates for both orientations.

Call `write_snapshot` from `save_snapshot` instead of `write_eddy` directly.

Remove procedure `write_aux`. Write to `ishape_last.txt` in procedure
`write_snapshot` and write `grid_nml` in procedure `input_ssh`. In
`input_ssh`, if `grid_nml.txt` already exists, check consistency with
input NetCDF files. Downgrade dummy arguments `corner_deg` and
`step_deg` of `input_ssh` to local variables. Read and write
`grid_nml` at SHPC level, only one file for both orientations and all
slices.

Assume that a slice is in a directory
"{shpc_dir}/{orientation}/Slice_{slice}" where shpc_dir can be any
name, orientation is "Anticyclones" or "Cyclones" and slice is an
integer. Do not read or create any longer a file "orientation.txt" in
the slice directory. Add procedure `get_slice_dir`. Add dummy
arguments cyclone and slice to procedure `shpc_open`. Add dummy
argument slice to procedure `shpc_create`.

The bug existed since commit 627df958.

Define two variables `hshp_in` and `hshp_out` to avoid aliases in
arguments of `shpc_create`. I have encountered a run which crashed there.

Rename procedure `write_snapshot` to `save_snapshot`.

Move `Common/write_snapshot.f90` to `Overlap/Tests/save_snapshot.f90`.

Split derived type `shpc_slice_handler` into `shpc_slice_handler` and
`shpc_slice_meta out`. Do not mix what is necessary to open, create
and close, analogous to a logical unit, with what comes from reading
the files.

Because we are going to use it in `Inst_eddies` too.

Create component `unit` for `ishape_last.txt` in derived type
`shpc_slice_handler`. Open, create and close `ishape_last.txt` at the
same time we open, create and close the shapefiles. So we use
`read_opcol` instead of `read_column` when we need to read
`ishape_last.txt`.

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

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 tests for a case where the speed is not defined on a whole segment.

Add a test that is going through `is_node_type` with an integer label.

Following update of `test_compare.py`.

Use the env keyword of `test_compare.py` rather than setting env on
the command line. This seems a little clearer and it allows us to
remove the stdout line in the test description. The possibility to add
env was added to `test_compare.py` in commit 4964d767 of the
`Test_compare` repository, after replacing mpiexec by `$mpiexec` in
`eddy_graph.sh`, in commit 850efa4b of the present repository.

In particular for several SHPC.

Generalize `test_read_snapshot` to accept several SHPC onthe command line.