compute fep examples ==================== * `CH4hyd` -- free energy of hydration of methane (very simple). FEP and TI methods. * `CH4-CF4` -- free energy difference of transforming methane into perfluoromethane, in water (simple). BAR method. * `CC-CO` -- free energy difference of transforming ethane into methanol, in water (more complex). FEP, TI and BAR methods.