merge Amaury.Bilocoq/waves (amaury) into feature_vii + cleaning. Tests to be fixed.

Squashed commit of the following:

commit c6c791de
Author: AmauryBilocq <amaury.bilocq@gmail.com>
Date:   Fri Nov 6 12:03:29 2020 +0100

    Quasi-simultaneous coupler for VII with test cases

commit 0cbee7e4
Merge: fd99999c ca62dcef
Author: AmauryBilocq <amaury.bilocq@gmail.com>
Date:   Sun Apr 26 14:58:26 2020 +0200

    V1.0 Viscous Inviscid interaction with direct solver

commit fd99999c
Author: AmauryBilocq <amaury.bilocq@gmail.com>
Date:   Sun Apr 26 14:47:01 2020 +0200

    V1.0 Viscous Inviscid interaction with direct solver

commit ca62dcef
Author: AmauryBilocq <amaury.bilocq@gmail.com>
Date:   Wed Oct 30 18:41:17 2019 +0100

    Trial to find the stagnation point