Nicolas Tancogne-Dejean requested to merge poisson_fft_shells into develop Jan 14, 2020

Description

The 3D FFT poisson solver now only consider closed shells. Includes also minor changes. This is part of the !555 (closed) .

News snippet

The 3D FFT poisson solver now only consider closed shells.

Checklist

I have checked that my code follows the Octopus coding standards
I have added tests for all the new features added in this request.