added gps support

added compass support
added ui elements for gps and compass
added support for writing sensor data

sensors/android/CompassSensorAndroid.h

@@ -0,0 +1,63 @@
+#ifndef COMPASSSENSORANDROID_H
+#define COMPASSSENSORANDROID_H
+
+#ifdef ANDROID
+
+#include <sstream>
+
+#include "../CompassSensor.h"
+
+#include <QtSensors/QCompass>
+
+class CompassSensorAndroid : public CompassSensor {
+
+private:
+
+	QCompass compass;
+
+	/** hidden ctor. use singleton */
+	CompassSensorAndroid() {
+		;
+	}
+
+	bool started = false;
+
+public:
+
+	/** singleton access */
+	static CompassSensorAndroid& get() {
+		static CompassSensorAndroid compass;
+		return compass;
+	}
+
+	void start() override {
+
+		if (started) {return;}
+		started = true;
+
+		auto onSensorData = [&] () {
+			CompassData data(
+				compass.reading()->azimuth(),
+				compass.reading()->calibrationLevel()
+			);
+			informListeners(data);
+		};
+
+		compass.connect(&compass, &QCompass::readingChanged, onSensorData);
+		compass.start();
+
+	}
+
+	bool isRunning() const override {
+		return started;
+	}
+
+	void stop() override {
+		throw "TODO";
+	}
+
+};
+
+#endif
+
+#endif // COMPASSSENSORANDROID_H