Keep the t variable monotonic in the simulation

Otherwise it causes stopping sending MAVLink and other bugs

gazebo/Arduino.h

@@ -134,7 +134,8 @@ void delay(uint32_t ms) {
 }
 
 unsigned long __micros;
+unsigned long __resetTime = 0;
 
 unsigned long micros() {
-	return __micros;
+	return __micros + __resetTime; // keep the time monotonic
 }

gazebo/simulator.cpp

@@ -55,6 +55,7 @@ public:
 
 	void OnReset() {
 		attitude = Quaternion(); // reset estimated attitude
+		__resetTime += __micros;
 		gzmsg << "Flix plugin reset" << endl;
 	}