+/**
+ * \brief Launches the simulation.
+ *
+ * The function will execute the \ref SD_READY ready tasks.
+ * The simulation will be stopped when its time reaches \a how_long,
+ * when a watch point is reached, or when no more task can be executed.
+ * Then you can call SD_simulate() again.
+ *
+ * \param how_long maximum duration of the simulation
+ * \return a NULL-terminated array of \ref SD_task_t whose state has changed.
+ * \see SD_task_schedule(), SD_task_watch()