Build failure on Windows

[star-hengxing]

octomap\src\compare_octrees.cpp(136): error C2039: '_isnan': is not a member of 'std'

octomap/octomap/src/compare_octrees.cpp

Lines 42 to 44 in 863e069

	#ifdef _MSC_VER // fix missing isnan for VC++
	#define isnan(x) _isnan(x)
	#endif

->

#if defined(_MSVC_LANG) && _MSVC_LANG < 201103L
#define isnan(x) _isnan(x)   
#endif 

[star-hengxing]

I found this #417

[ahornung]

Fixed with #417