USe a common default geodesic object instead of duplicate copies.

All used functions are constant, and don't require unique instantiations for thread safety.

scwx-qt/source/scwx/qt/util/geographic_lib.hpp

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <GeographicLib/Geodesic.hpp>
+
+namespace scwx
+{
+namespace qt
+{
+namespace util
+{
+namespace GeographicLib
+{
+
+/**
+ * Get the default geodesic for the WGS84 ellipsoid.
+ *
+ * return WGS84 ellipsoid geodesic
+ */
+const ::GeographicLib::Geodesic& DefaultGeodesic();
+
+} // namespace GeographicLib
+} // namespace util
+} // namespace qt
+} // namespace scwx