Update project structure and build process

libwallet/musig/musig_main_impl.h

@@ -0,0 +1,18 @@
+/**********************************************************************
+ * Copyright (c) 2018 Andrew Poelstra, Jonas Nick                     *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef _SECP256K1_MODULE_MUSIG_MAIN_
+#define _SECP256K1_MODULE_MUSIG_MAIN_
+
+#include <stdint.h>
+#include "secp256k1.h"
+#include "secp256k1_musig.h"
+#include "hash.h"
+#include "keyagg_impl.h"
+#include "session_impl.h"
+#include "adaptor_impl.h"
+
+#endif