General processing adaptations for Scenario Explorer

[maxnutz]

• processing of timesteps introduces a timedelta of one hour, accounting for UTC-time. Scenario Explorer then substracts one hour leading to curious timesteps - expecially for yearly aggregated data. Therefore switching from 1 hour timedelta to 0 hour timedelta will resolve the problem.
• for yearly aggregated data, the timesamps need to be converted to "str" or "float" (2020, 2030, ...)