Description

Fix the occupation guessing code, which was not correct for some pseudopotentials after the prior changes.
The file D.hgh was not migrated properly to the usual HGH format.
Avoids to access arrays outside of their bounds.

News snippet

Bugfixes for guess the atomic occupations for HGH pseudopotentials.

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.