Remove isnan() and isinf() templated from QGC.h only if prior to Visual Studio 2013

src/QGC.h

@@ -33,6 +33,24 @@
 
 /* Windows fixes */
 #ifdef _MSC_VER
+#if (_MSC_VER < 1800)	/* only PRIOR to Visual Studio 2013 */
+/* Needed define for Eigen */
+//#define NOMINMAX
+#include <limits>
+template<typename T>
+inline bool isnan(T value)
+{
+	return value != value;
+
+}
+
+// requires #include <limits>
+template<typename T>
+inline bool isinf(T value)
+{
+	return (value == std::numeric_limits<T>::infinity() || (-1 * value) == std::numeric_limits<T>::infinity()) && std::numeric_limits<T>::has_infinity;
+}
+#endif
 #elif defined __APPLE__
 #include <cmath>
 #ifndef isnan