Squashed commit of the following:

commit 997c1138f549766d797f1ba6da26e1e8394387e2
Author: emeric <itmfr@yahoo.fr>
Date:   Sat Jan 10 17:50:20 2015 +0100

    Implemented save, load and delete playlists

commit bee08a16b544bb21785c45f083ab7c10e65bfa6e
Author: emeric <itmfr@yahoo.fr>
Date:   Thu Jan 8 23:46:43 2015 +0100

    Reworked the database code layout in order to add playlists

src/database/Types.hpp

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2015 Emeric Poupon
+ *
+ * This file is part of LMS.
+ *
+ * LMS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+// header file aimed to ease database class declarations
+
+#include "Track.hpp"
+#include "Playlist.hpp"
+#include "Video.hpp"
+#include "MediaDirectory.hpp"
+#include "User.hpp"
+