Improve losslib.get_PoEs to compute PoEs for any number of damage states
losscalculator is limited to only four damage states (slight, moderate, extensive and complete); Therefore the function
losslib.get_PoEs() is designed to compute PoEs for only 4 damage states.
But as we plan to improve the calculator,
losslib.get_PoEs() should change to be able to automatically detect the number of damage states (number of lines in the fragility function -1) and do as many computations to get PoEs for all available damage states.