use std::isnan since c++11 provides it and wxIsNan is broken in c++11

src/widgets/numformatter.cpp

@@ -32,7 +32,7 @@
 #include <wx/intl.h>
 
 #include <locale.h> // for setlocale and LC_ALL
-#include <math.h>
+#include <cmath>
 #include <wx/log.h>
 
 // ----------------------------------------------------------------------------
@@ -134,11 +134,11 @@ wxString NumberFormatter::ToString(double val, int precision, int style)
         format.Printf(wxT("%%.%df"), precision);
     }
 
-    if (isnan(val))
+    if (std::isnan(val))
     {
         return _("NaN");
     }
-    if (isinf(val))
+    if (std::isinf(val))
     {
         return _("-Infinity");
     }