Add ability to limit the # of levels of each dopant

[sivonxay]

Some dopants (such as Er) have many more energy levels than others. It is unlikely that we get much additional accuracy from including these extra energy levels into the simulation.

Proposed changes:

1. Add the ability to limit the energy levels by energy value.
2. Add the ability to limit the max energy of dopant states in the SpectralKinetics module.