ms visual studio 2013 support

not full support

I2PEndian.h

@@ -0,0 +1,19 @@
+#ifndef I2PENDIAN_H__
+#define I2PENDIAN_H__
+
+#ifndef _WIN32
+#include <endian.h>
+#else
+#include <cstdint>
+
+uint16_t htobe16(uint16_t int16);
+uint32_t htobe32(uint32_t int32);
+uint64_t htobe64(uint64_t int64);
+
+uint16_t be16toh(uint16_t big16);
+uint32_t be32toh(uint32_t big32);
+uint64_t be64toh(uint64_t big64);
+
+#endif
+
+#endif // I2PENDIAN_H__