Fixes for mixed-periodicity and to Wannier90 interface for non-cubic systems

Description

Several fixes to mixed-periodicity related to the change of definition of the lattice vectors along non-periodic dimensions.

Fix in Wannier90 interface: fix the conversion from reduced to absolute coordinates for the G vectors used to construct the overlap matrix. This was wrong by a transpose and the code was therefore correct for cubic systems.

News snippet

Fixes for mixed-periodicity and to Wannier90 interface for non-cubic systems.

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.