Initial working version.

All terms yield the same energies as Gromacs and CHARMM. Using a distance-dependent dielectric constant in the Coulomb term gives same energies as CHARMM. 

Known issues:
EEF1-SB specific charges need validation. Furthermore no EEF1-SB specific charges exist for  N-term Proline and Glycine. Currently CHARMM36 charges are implemented for Proline, and generic charges are used for Glycine.
E_psi torsion correction needs validation, but no reference code seems to exist.
Parameter filepath's are still hardcoded.