ADD: new track message, Entity class and Position class

libs/geographiclib/examples/example-GeographicErr.cpp

@@ -0,0 +1,16 @@
+// Example of using the GeographicLib::GeographicErr class
+
+#include <iostream>
+#include <GeographicLib/Constants.hpp>
+
+using namespace std;
+using namespace GeographicLib;
+
+int main() {
+  try {
+    throw GeographicErr("Test throwing an exception");
+  }
+  catch (const GeographicErr& e) {
+    cout << "Caught exception: " << e.what() << "\n";
+  }
+}