Add CashAddr Address Format

Ported from Bitcoin Unlimited, Bitcoin ABC

src/fs.h

@@ -0,0 +1,24 @@
+// Copyright (c) 2017 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_FS_H
+#define BITCOIN_FS_H
+
+#include <stdio.h>
+#include <string>
+
+#include <boost/filesystem.hpp>
+#include <boost/filesystem/fstream.hpp>
+#include <boost/filesystem/detail/utf8_codecvt_facet.hpp>
+
+/** Filesystem operations and types */
+namespace fs = boost::filesystem;
+
+/** Bridge operations to C stdio */
+namespace fsbridge {
+    FILE *fopen(const fs::path& p, const char *mode);
+    FILE *freopen(const fs::path& p, const char *mode, FILE *stream);
+};
+
+#endif