Reinstate accidentally removed code in create_next_nearest_orbs.
Reinstate accidentally removed code in create_next_nearest_orbs.

123f2d accidentally removed the core logic in create_next_nearest orbs
and caused the next nearest orbital list not to be set.  Reinstate this
code (modified to accomodate the change in data structure).

Reported by: Nick Blunt.

hande-qmc/hande,ruthfranklin/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande