Clarify the use of t_end, t_horizon, intervalLength, reserveLength etc.
E.g. if the user wants to have 48 active time steps in the horizon, should t_horizon be 48 or 49? Same thing should also be clarified for other settings describing the length of different periods. Furthermore, whether the last time steps are shown in the results.gdx or not, seems to depend on whether there are time series data defined also for t000000.