Vehicles that reach desired SOC should disconnect from opps

[j-brendel]

Vehicles that reach desired SOC should disconnect from opps

Example from simulation_timeseries_xxx.csv

The number of occupied stations should then decrease, so the vehicle makes space for the next vehicle to be charged, if number of occupied stations are limited.

[j-brendel]

It also occurs, that if the number of cs is limited in electrified stations, the # of occupied stations is still higher. This might have the same cause?

[stefansc1]

Distributed strategy already limits connected vehicles to n_charging_stations (more vehicles might be connected, but do not draw power). Solution is to count CS that actually deliver power, which is addressed in #93