Correction in input data for specific simulation period

[Hoppe-J]

changes in simulation time span --> use utc for lpg and weather input data, so every time period can simulated

Problem bevor was, that simulation starts every single time from 01. January even the simulation parameter where changed --> only in post processing the timestamps were correct from simulationsparameters, but now every time span can simulate and the specific period is loaded from lpg and weather data ( see issue #347)