Add project files.

AssetStudio/Extensions/StreamExtensions.cs

@@ -0,0 +1,24 @@
+using System.IO;
+
+namespace AssetStudio
+{
+    public static class StreamExtensions
+    {
+        private const int BufferSize = 81920;
+
+        public static void CopyTo(this Stream source, Stream destination, long size)
+        {
+            var buffer = new byte[BufferSize];
+            for (var left = size; left > 0; left -= BufferSize)
+            {
+                int toRead = BufferSize < left ? BufferSize : (int)left;
+                int read = source.Read(buffer, 0, toRead);
+                destination.Write(buffer, 0, read);
+                if (read != toRead)
+                {
+                    return;
+                }
+            }
+        }
+    }
+}