Get rid of MSVC's __int64

Use either int64_t, uint64_t or long long and unsigned long long, defined as per C++11 standard

Minecraft.World/AddSnowLayer.h

@@ -4,6 +4,6 @@
 class AddSnowLayer : public Layer
 {
 public:
-    AddSnowLayer(__int64 seedMixup, shared_ptr<Layer> parent);
+    AddSnowLayer(int64_t seedMixup, shared_ptr<Layer> parent);
     virtual intArray getArea(int xo, int yo, int w, int h);
 };