Add outputtype module

Moves OutputType into its own module

src/outputtype.h

@@ -0,0 +1,41 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2017 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_OUTPUTTYPE_H
+#define BITCOIN_OUTPUTTYPE_H
+
+#include <script/standard.h>
+
+#include <string>
+#include <vector>
+
+enum class OutputType {
+    LEGACY,
+    P2SH_SEGWIT,
+    BECH32,
+
+    /**
+     * Special output type for change outputs only. Automatically choose type
+     * based on address type setting and the types other of non-change outputs
+     * (see -changetype option documentation and implementation in
+     * CWallet::TransactionChangeType for details).
+     */
+    CHANGE_AUTO,
+};
+
+bool ParseOutputType(const std::string& str, OutputType& output_type);
+const std::string& FormatOutputType(OutputType type);
+
+/**
+ * Get a destination of the requested type (if possible) to the specified key.
+ * The caller must make sure LearnRelatedScripts has been called beforehand.
+ */
+CTxDestination GetDestinationForKey(const CPubKey& key, OutputType);
+
+/** Get all destinations (potentially) supported by the wallet for the given key. */
+std::vector<CTxDestination> GetAllDestinationsForKey(const CPubKey& key);
+
+#endif // BITCOIN_OUTPUTTYPE_H
+