Ref T215, remember last server and model as cache value

* also remember last server not VATSIM server
* remember last model used
* server list selector uses remembered value
* login component sets those values

src/blackmisc/network/data/lastserver.h

@@ -0,0 +1,37 @@
+/* Copyright (C) 2017
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
+ * including this file, may be copied, modified, propagated, or distributed except according to the terms
+ * contained in the LICENSE file.
+ */
+
+//! \file
+
+#ifndef BLACKMISC_NETWORK_DATA_LASTSERVER_H
+#define BLACKMISC_NETWORK_DATA_LASTSERVER_H
+
+#include "../server.h"
+#include "blackmisc/datacache.h"
+
+namespace BlackMisc
+{
+    namespace Network
+    {
+        namespace Data
+        {
+            //! Trait for last (most recently) used server and user
+            struct TLastServer : public TDataTrait<CServer>
+            {
+                //! Key in data cache
+                static const char *key() { return "lastserver"; }
+
+                //! First load is synchronous
+                static constexpr bool isPinned() { return true; }
+            };
+        } // ns
+    } // ns
+} // ns
+
+#endif // guard