ADD: new track message, Entity class and Position class

libs/geographiclib/examples/example-MGRS.cpp

@@ -0,0 +1,42 @@
+// Example of using the GeographicLib::MGRS class
+
+#include <iostream>
+#include <exception>
+#include <string>
+#include <GeographicLib/UTMUPS.hpp>
+#include <GeographicLib/MGRS.hpp>
+
+using namespace std;
+using namespace GeographicLib;
+
+int main() {
+  try {
+    // See also example-GeoCoords.cpp
+    {
+      // Sample forward calculation
+      double lat = 33.3, lon = 44.4; // Baghdad
+      int zone;
+      bool northp;
+      double x, y;
+      UTMUPS::Forward(lat, lon, zone, northp, x, y);
+      string mgrs;
+      MGRS::Forward(zone, northp, x, y, lat, 5, mgrs);
+      cout << mgrs << "\n";
+    }
+    {
+      // Sample reverse calculation
+      string mgrs = "38SMB4488";
+      int zone, prec;
+      bool northp;
+      double x, y;
+      MGRS::Reverse(mgrs, zone, northp, x, y, prec);
+      double lat, lon;
+      UTMUPS::Reverse(zone, northp, x, y, lat, lon);
+      cout << prec << " " << lat << " " << lon << "\n";
+    }
+  }
+  catch (const exception& e) {
+    cerr << "Caught exception: " << e.what() << "\n";
+    return 1;
+  }
+}