Extend code to handle arbitrary configration of spheres

[ronandrevon]

Using the translation theorem for spherical harmonics including values of m>0, the formulation can be written to allow for solving the problem with arbitrary configurations of quantum dots. A new base class would have to be implemented similar to HardSphereArrayBase.

[kitine]

Continuity check :

[kitine]

Far field :

[ronandrevon]

stable