set default method to chacha20-ietf-poly1305 in all place...

shadowsocks-csharp/Encryption/EncryptorFactory.cs

@@ -70,7 +70,7 @@ namespace Shadowsocks.Encryption
         {
             if (method.IsNullOrEmpty())
             {
-                method = "aes-256-cfb";
+                method = Model.Server.DefaultMethod;
             }
 
             method = method.ToLowerInvariant();

shadowsocks-csharp/Model/Server.cs

@@ -11,6 +11,9 @@ namespace Shadowsocks.Model
     [Serializable]
     public class Server
     {
+        public const string DefaultMethod = "chacha20-ietf-poly1305";
+        public const int DefaultPort = 8388;
+
         #region ParseLegacyURL
         public static readonly Regex
             UrlFinder = new Regex(@"ss://(?<base64>[A-Za-z0-9+-/=_]+)(?:#(?<tag>\S+))?", RegexOptions.IgnoreCase),
@@ -69,8 +72,8 @@ namespace Shadowsocks.Model
         public Server()
         {
             server = "";
-            server_port = 8388;
-            method = "chacha20-ietf-poly1305";
+            server_port = DefaultPort;
+            method = DefaultMethod;
             plugin = "";
             plugin_opts = "";
             plugin_args = "";

shadowsocks-csharp/View/ConfigForm.cs

@@ -316,7 +316,7 @@ namespace Shadowsocks.View
             IPTextBox.Text = server.server;
             ServerPortTextBox.Text = server.server_port.ToString();
             PasswordTextBox.Text = server.password;
-            EncryptionSelect.Text = server.method ?? "aes-256-cfb";
+            EncryptionSelect.Text = server.method ?? Server.DefaultMethod;
             PluginTextBox.Text = server.plugin;
             PluginOptionsTextBox.Text = server.plugin_opts;
             PluginArgumentsTextBox.Text = server.plugin_args;