Implement correction schemes for charged systems

[davidbowler]

There are a variety of correction schemes for charged periodic systems which should be implemented.

[davidbowler]

The dipole correction scheme of Neugebauer and M. Scheffler, Phys. Rev. B 46, 16 067 (1992) has been implemented in the branch f-dipole-correction

[davidbowler]

The surface dipole correction scheme has been implemented and merged in #405 . We should consider correction schemes for charged bulk systems along the lines of Makov-Payne etc.