Bugfix: lsize corresponds to half of the size of the simulation box in the case of a parallelepiped.

Description

The lengths of the axis of the simulation box were displayed wrong by a factor of two for parallelepiped box.

News snippet

The lengths of the axis of the simulation box were displayed wrong by a factor of two for parallelepiped box.

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.