fixed some compiler warnings

added equality checks to sensor-data classes
more robust sensor reader [fixed some issues]
added support for gps
added support for compass
added sensor-data-writer
added test-cases
minor changes

main.cpp

@@ -29,7 +29,7 @@ int main(int argc, char** argv) {
     //::testing::GTEST_FLAG(filter) = "*WiFiOptimizer*";
 
 
-	::testing::GTEST_FLAG(filter) = "*FloorplanCeilings*";
+	::testing::GTEST_FLAG(filter) = "*Offline.readWrite*";
     //::testing::GTEST_FLAG(filter) = "*Barometer*";
 	//::testing::GTEST_FLAG(filter) = "*GridWalk2RelPressure*";