Laser: changed global time zeroing strategy

    std::map<std::shared_ptr<Detector>, std::vector<MCParticle>> mc_particles;

    std::map<std::shared_ptr<Detector>, std::vector<DepositedCharge>> deposited_charges;

    // Lambda generator to yield pulse shape

    auto yield_starting_time = [&]() {

        int cut_sigmas = 4;

        double result = -1;

        while(result < 0) {

            result =

                allpix::normal_distribution<double>(cut_sigmas * pulse_duration_, pulse_duration_)(event->getRandomEngine());

        }

        return result;

    };

    // Containers for timestamps

    // Starting time points are generated in advance to correctly shift zero afterwards

    std::vector<double> starting_times(number_of_photons_);

    std::for_each(begin(starting_times), end(starting_times), [&](auto& item) {

        item = allpix::normal_distribution<double>(0, pulse_duration_)(event->getRandomEngine());

        item = yield_starting_time();

        h_pulse_shape_->Fill(item);

    });

    std::sort(begin(starting_times), end(starting_times));

    double starting_time_offset = starting_times[0];

    std::for_each(

        begin(starting_times), end(starting_times), [starting_time_offset](auto& item) { item -= starting_time_offset; });

    for(const auto& item : starting_times) {

        h_pulse_shape_->Fill(item);

    }

    // To correctly offset local time for each detector

    std::map<std::shared_ptr<Detector>, double> local_time_offsets;