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/Playlist.hpp

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2014 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/>.
+ */
+
+#ifndef DATABASE_PLAYLIST_HPP
+#define DATABASE_PLAYLIST_HPP
+
+#include <Wt/Dbo/Dbo>
+
+namespace Database {
+
+class PlaylistEntry;
+class User;
+class Track;
+
+class Playlist
+{
+	public:
+		typedef Wt::Dbo::ptr<Playlist> pointer;
+
+		Playlist();
+		Playlist(std::string name, bool isPublic, Wt::Dbo::ptr<User> user);
+
+		// Search utility
+		static pointer	get(Wt::Dbo::Session& session, std::string name, Wt::Dbo::ptr<User> user);
+
+		// ordered by name
+		static std::vector<pointer>	get(Wt::Dbo::Session& session, Wt::Dbo::ptr<User> user);
+
+		// Create utility
+		static pointer	create(Wt::Dbo::Session& session, std::string name, bool isPublic, Wt::Dbo::ptr<User> user);
+
+		// Accessors
+		std::string	getName() const { return _name; }
+
+		template<class Action>
+		void persist(Action& a)
+		{
+			Wt::Dbo::field(a,	_name,		"name");
+			Wt::Dbo::field(a,	_isPublic,	"public");
+			Wt::Dbo::belongsTo(a,	_user,		"user", Wt::Dbo::OnDeleteCascade);
+			Wt::Dbo::hasMany(a, _entries, Wt::Dbo::ManyToOne, "playlist");
+		}
+
+	private:
+
+		std::string		_name;
+		bool			_isPublic;
+		Wt::Dbo::ptr<User>	_user;
+		Wt::Dbo::collection< Wt::Dbo::ptr<PlaylistEntry> > _entries;
+
+};
+
+class PlaylistEntry
+{
+	public:
+
+		typedef Wt::Dbo::ptr<PlaylistEntry> pointer;
+
+		PlaylistEntry();
+		PlaylistEntry(Wt::Dbo::ptr<Track> rack, Wt::Dbo::ptr<Playlist> playlist, int position);
+
+		// Search utility
+
+		// Get the position ordered track id list
+		static std::vector<Track::id_type> getEntries(Wt::Dbo::Session& session,Wt::Dbo::ptr<Playlist> playlist);
+
+		// Create utility
+		static pointer	create(Wt::Dbo::Session& session, Wt::Dbo::ptr<Track> track, Wt::Dbo::ptr<Playlist> playlist, int position);
+
+		// Accesors
+		Wt::Dbo::ptr<Track>	getTrack() const { return _track; }
+
+		template<class Action>
+		void persist(Action& a)
+		{
+			Wt::Dbo::field(a,	_pos,	"pos");
+			Wt::Dbo::belongsTo(a,	_track, "track", Wt::Dbo::OnDeleteCascade);
+			Wt::Dbo::belongsTo(a,	_playlist, "playlist", Wt::Dbo::OnDeleteCascade);
+		}
+
+	private:
+
+		int			_pos;
+		Wt::Dbo::ptr<Track>	_track;
+		Wt::Dbo::ptr<Playlist>	_playlist;
+};
+
+} // namespace Database
+
+#endif