Simulator: Make battery discharging configurable.

src/modules/simulator/simulator_mavlink.cpp

@@ -356,7 +356,7 @@ void Simulator::handle_message(mavlink_message_t *msg, bool publish)
 			update_sensors(&imu);
 
 			// battery simulation
-			const float discharge_interval_us = 60 * 1000 * 1000;
+			const float discharge_interval_us = _battery_drain_interval_s.get() * 1000 * 1000;
 
 			bool armed = (_vehicle_status.arming_state == vehicle_status_s::ARMING_STATE_ARMED);
 
@@ -625,6 +625,7 @@ void Simulator::send()
 
 		if (fds[0].revents & POLLIN) {
 			// got new data to read, update all topics
+			parameters_update(false);
 			poll_topics();
 			send_controls();
 		}