performance enhancements

memory enhancements
prevent starting sensors more than once
fix for wifi lag issues
map scaling for huge buildings

sensors/android/GyroscopeSensorAndroid.h

@@ -22,6 +22,8 @@ private:
 		;
 	}
 
+	bool started = false;
+
 public:
 
 	/** singleton access */
@@ -36,18 +38,26 @@ public:
 
 	void start() override {
 
+		if (started) {return;}
+		started = true;
+
 		auto onSensorData = [&] () {
 			GyroscopeData data(degToRad(gyro.reading()->x()), degToRad(gyro.reading()->y()), degToRad(gyro.reading()->z()));
 			informListeners(data);
+//			const Timestamp now = Timestamp::fromRunningTime();
+//			Log::add("123", "ts:" + std::to_string(now.ms()));
 		};
 
+		// gyroscope is usually not as fast as the acceleromter -> limiting not needed
+		//gyro.setDataRate(200);
+
 		gyro.connect(&gyro, &QGyroscope::readingChanged, onSensorData);
 		gyro.start();
 
 	}
 
 	bool isRunning() const override {
-		return gyro.isActive();
+		return started;
 	}
 
 	void stop() override {