Implement IOSHttpRequest and IOSHttpResponse http interfaces and use instead of OSHttpRequest/OSHttpResponse.

This is required for the substitution of different HTTP servers or the newer HttpServer.dll without having to commit to a particular implementation.
This is also required to write regression tests that involve the HTTP layer.
If you need to recompile, all you need to do is replace OSHttpRequest/OSHttpResponse references with IOSHttpRequest/IOSHttpResponse.

OpenSim/Framework/Servers/HttpServer/Interfaces/IOSHttpResponse.cs

@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSimulator Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+using System;
+using System.Collections;
+using System.Collections.Specialized;
+using System.IO;
+using System.Net;
+using System.Text;
+using System.Web;
+
+namespace OpenSim.Framework.Servers.HttpServer
+{
+    public interface IOSHttpResponse
+    {
+        /// <summary>
+        /// Content type property.
+        /// </summary>
+        /// <remarks>
+        /// Setting this property will also set IsContentTypeSet to
+        /// true.
+        /// </remarks>
+        string ContentType { get; set; }
+
+        /// <summary>
+        /// Boolean property indicating whether the content type
+        /// property actively has been set.
+        /// </summary>
+        /// <remarks>
+        /// IsContentTypeSet will go away together with .NET base.
+        /// </remarks>
+        // public bool IsContentTypeSet
+        // {
+        //     get { return _contentTypeSet; }
+        // }
+        // private bool _contentTypeSet;
+
+        /// <summary>
+        /// Length of the body content; 0 if there is no body.
+        /// </summary>
+        long ContentLength { get; set; }
+
+        /// <summary>
+        /// Alias for ContentLength.
+        /// </summary>
+        long ContentLength64 { get; set; }
+
+        /// <summary>
+        /// Encoding of the body content.
+        /// </summary>
+        Encoding ContentEncoding { get; set; }
+
+        bool KeepAlive { get; set; }
+
+        /// <summary>
+        /// Get or set the keep alive timeout property (default is
+        /// 20). Setting this to 0 also disables KeepAlive. Setting
+        /// this to something else but 0 also enable KeepAlive.
+        /// </summary>
+        int KeepAliveTimeout { get; set; }
+
+        /// <summary>
+        /// Return the output stream feeding the body.
+        /// </summary>
+        /// <remarks>
+        /// On its way out...
+        /// </remarks>
+        Stream OutputStream { get; }
+
+        string ProtocolVersion { get; set; }
+
+        /// <summary>
+        /// Return the output stream feeding the body.
+        /// </summary>
+        Stream Body { get; }
+
+        /// <summary>
+        /// Set a redirct location.
+        /// </summary>
+        string RedirectLocation { set; }
+
+        /// <summary>
+        /// Chunk transfers.
+        /// </summary>
+        bool SendChunked { get; set; }
+
+        /// <summary>
+        /// HTTP status code.
+        /// </summary>
+        int StatusCode { get; set; }
+
+        /// <summary>
+        /// HTTP status description.
+        /// </summary>
+        string StatusDescription { get; set; }
+
+        bool ReuseContext { get; set; }
+
+        /// <summary>
+        /// Add a header field and content to the response.
+        /// </summary>
+        /// <param name="key">string containing the header field
+        /// name</param>
+        /// <param name="value">string containing the header field
+        /// value</param>
+        void AddHeader(string key, string value);
+
+        /// <summary>
+        /// Send the response back to the remote client
+        /// </summary>
+        void Send();
+    }
+}
+