And it is then conveninent to choose it from the command line.

So read `grid_ml.txt` at the beginning of the script and not in
function `plot_grid_bb`, and pass `grid_nml` instead of `shpc_dir` to
function `plot_grid_bb`.

The script `plot_eddy_contours.py` was becoming too complicated.

So we can use the script on an SHPC converted from Matlab.

An SHPC now contains a single orientation (since after v0.12).

There may be four shapefiles with the centroid layer.

Replace `SHPC_(anti|cyclo)_all_dates` by `SHPC_(anti|cyclo)`.

Move the definition of colors out of the loop on shapes, since the
orientation is now the same for all shapes.

This SHPC was made with an old version of `inst_eddies`: it contained
cyclones and anticyclones output together. We create a test `Region_6`
instead.

The orientation is no longer a DBF field.

Instead of `d_init`, `ishape_last` and `reader_extr`.

Instead of readers. Preparing for extension to receive orientation.

Instead of `readers_all`.

Instead of several pieces of it. Clearer and more concise.

Instead of several values of the handler dictionary. Clearer and more concise.

Instead of tuple. Preparing for extensions to return orientation and
to deal with several SHPC.

Rename triplet to collection, `shp_tr` to shpc, shpt to shpc in
comments, identifiers and file names.

Since it is now possible to have one or more SHPC as arguments.

This SHPC was made with an old version of `inst_eddies`: it contains
cyclones and anticyclones output together. We use
`$tests_old_dir/Inst_eddies_loop` instead. See also commit 8ed324ff.

This is necessary since we now output separately cyclones and
anticyclones from `inst_eddies.`

This is more comfortable. Furthermore, it is going to be necessary
when we extend the script to several input SHPC.

For an animation, we want several dates so we need `ishape_last.txt`.

`make_animation` seems too general, the reader may think it is an
object of Matplotlib.

Run it with two dates and the new input NetCDF files. Two dates so it
can replace the SHPC that was in `$src_dir/Tests/Eddies_region_4`.

Instead of `$src_dir/Tests/Eddies_region_4`. Because
`$src_dir/Tests/Eddies_region_4` was made with an old version of
`inst_eddies`: cyclones and anticyclones output together.

Since it is a test on script which is in Analysis.

To regroup statements which depend on the shapefiles.

Move `Overlap/Tests/Input/Region_4/Eddies_region_4` to Tests. Now used
both in `Inst_eddies` and `Overlap`.