The script may abort because of wrong arguments. It is better not to
have touched anything in that case.

Clearer for the user.

Bug was introduced in commit 8c91ffe5.

Create separate collections of shapefiles for cyclones and anticyclones.

Because we want to use the module parser from dateutil.

I do not see a better way than to ask the user to provide the template
of basename as an additional argument. We cannot do as in
`Convert_Matlab/inst_eddies_v6.py`, that is try a list of templates,
because here the file names could be anything.

So we no longer have to create a symbolic link when we run
`inst_eddies.py`.

Preparing for configuration of location of binary executable.

`cropped.nc` does not exist if not `args.bbox`.

Better to check this before the creation of all the temporary files
and links, so the user does not have to clean them up before running
again.

New script to loop on detection of instantaneous eddies.