Use unordered map for VS2015

Plugin-PoissonReconstruction/PoissonReconstruction/Hash.h

 #ifndef HASH_INCLUDED
 #define HASH_INCLUDED
 #ifdef WIN32
-#include <hash_map>
-using stdext::hash_map;
+
+  #if _MSC_VER >= 1900
+    #include <unordered_map>
+    #define hash_map std::unordered_map
+  #else
+    #include <hash_map>
+    using stdext::hash_map;
+  #endif
+
 #else // !WIN32
 
-#if (__GNUC__ * 10000  + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)>= 40300 //gcc >= 4.3
-#include <tr1/unordered_map>
-#define hash_map std::tr1::unordered_map
+  #if (__GNUC__ * 10000  + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)>= 40300 //gcc >= 4.3
+    #include <tr1/unordered_map>
+    #define hash_map std::tr1::unordered_map
 
-#else //GCC_VERSION < 40300
-#include <ext/hash_map>
-using namespace __gnu_cxx;
+  #else //GCC_VERSION < 40300
+    #include <ext/hash_map>
+    using namespace __gnu_cxx;
 
-namespace __gnu_cxx
-{
-  template<> struct hash<long long> {
-    size_t operator()(long long __x) const { return __x; }
-  };
-  template<> struct hash<const long long> {
-    size_t operator()(const long long __x) const { return __x; }
-  };
+    namespace __gnu_cxx
+    {  
+      template<> struct hash<long long> {
+        size_t operator()(long long __x) const { return __x; }
+      };
+      template<> struct hash<const long long> {
+        size_t operator()(const long long __x) const { return __x; }
+      };
   
   
-  template<> struct hash<unsigned long long> {
-    size_t operator()(unsigned long long __x) const { return __x; }
-  };
-  template<> struct hash<const unsigned long long> {
-    size_t operator()(const unsigned long long __x) const { return __x; }
-  };
-}
-#endif // gcc >= 4.3
+      template<> struct hash<unsigned long long> {
+        size_t operator()(unsigned long long __x) const { return __x; }
+      };
+      template<> struct hash<const unsigned long long> {
+        size_t operator()(const unsigned long long __x) const { return __x; }
+      };
+    }
+  #endif // gcc >= 4.3
 #endif // WIN32
 #endif // HASH_INCLUDED