Initial support code for beatmap loading

osu.Game/Beatmaps/IO/OszArchiveReader.cs

@@ -0,0 +1,42 @@
+using System;
+using System.IO;
+
+namespace osu.Game.Beatmaps.IO
+{
+    public class OszArchiveReader : ArchiveReader
+    {
+        static OszArchiveReader()
+        {
+            AddReader<OszArchiveReader>((storage, path) =>
+            {
+                using (var stream = storage.GetStream(path))
+                {
+                    // TODO: detect if osz
+                    return false;
+                }
+            });
+        }
+    
+        private Stream Archive { get; set; }
+    
+        public OszArchiveReader(Stream archive)
+        {
+            Archive = archive;
+        }
+
+        public override string[] ReadBeatmaps()
+        {
+            throw new NotImplementedException();
+        }
+
+        public override Stream ReadFile(string name)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override Metadata ReadMetadata()
+        {
+            throw new NotImplementedException();
+        }
+    }
+}