Bind3P water model

[orbeckst]

@iorga Maybe we should try out Mike Gilson's new Bind3P water model? They tested it with host-guest but perhaps it also works better for solvation free energies

See also #81

~p.s.: At the moment I cannot access the paper on chemarxiv https://chemrxiv.org/articles/Bind3P_A_Water_Model_to_Improve_the_Accuracy_of_Binding_Calculations/5848113 – I get~

message | "You are not authorized. Use the Authorization header to provide an acces token"
code | "Unauthorized"

update: allowing javascript on chemrxiv fixed the download issue