merge C&C and RA music player logic

mainly code cleanup, but with the following improvements:
- scroll to current song which fixes #3360 and overlapping label
- use Rules.InstalledMusic & Sound.MusicPlaying everywhere
- separated C&C install logic and log catched exceptions
- save the music settings on back/close

OpenRA.Mods.Cnc/Widgets/Logic/CncInstallMusicLogic.cs

@@ -0,0 +1,59 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2011 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.IO;
+using System.Linq;
+using OpenRA.FileFormats;
+using OpenRA.GameRules;
+using OpenRA.Mods.RA.Widgets.Logic;
+using OpenRA.Traits;
+using OpenRA.Widgets;
+
+namespace OpenRA.Mods.Cnc.Widgets.Logic
+{
+	public class CncInstallMusicLogic
+	{
+		[ObjectCreator.UseCtor]
+		public CncInstallMusicLogic(Widget widget, Action onExit)
+		{
+			var installButton = widget.GetOrNull<ButtonWidget>("INSTALL_BUTTON");
+			if (installButton != null)
+			{
+				Action afterInstall = () =>
+				{
+					try
+					{
+						var path = new string[] { Platform.SupportDir, "Content", WidgetUtils.ActiveModId() }.Aggregate(Path.Combine);
+						FileSystem.Mount(Path.Combine(path, "scores.mix"));
+						FileSystem.Mount(Path.Combine(path, "transit.mix"));
+
+						Rules.Music.Do(m => m.Value.Reload());
+
+						var musicPlayerLogic = (MusicPlayerLogic)installButton.Parent.LogicObject;
+						musicPlayerLogic.BuildMusicTable();
+					}
+					catch (Exception e)
+					{
+						Log.Write("debug", "Mounting the new mixfile and rebuild of scores list failed:\n{0}", e);
+					}
+				};
+
+				installButton.OnClick = () =>
+					Ui.OpenWindow("INSTALL_MUSIC_PANEL", new WidgetArgs() {
+						{ "afterInstall", afterInstall },
+						{ "filesToCopy", new[] { "SCORES.MIX" } },
+						{ "filesToExtract", new[] { "transit.mix" } },
+					});
+				installButton.IsVisible = () => Rules.InstalledMusic.ToArray().Length < 3; // HACK around music being split between transit.mix and scores.mix
+			}
+		}
+	}
+}