Simplify creation of new dynamic schedulers

For now, if someone wants to create a new dynamic scheduler (or transform a static scheduler into dynamic), here is what one should do:

• change super class from ISchedulingAlgorithm to DynScheduler
• add the call DynScheduler::on_simulation_start(date, batsim_config); at the beginning of on_simulation_start
• add the call DynScheduler::make_decisions(date, update_info, compare_info); at the end of make_decisions
• update the status of jobs with if (broker_enabled) broker->update_status_if_dyn_job(new_job_id, STATUS); each time the scheduler adds or rejects a job

This should be made easier by hiding these calls somehow.