Revert "THRIFT-4982 Remove deprecated C# bindings from the code base"

Only compiler, test, lib and tutorial code.
diff --git a/lib/csharp/src/Protocol/TProtocolException.cs b/lib/csharp/src/Protocol/TProtocolException.cs
new file mode 100644
index 0000000..7bef236
--- /dev/null
+++ b/lib/csharp/src/Protocol/TProtocolException.cs
@@ -0,0 +1,67 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ * Contains some contributions under the Thrift Software License.
+ * Please see doc/old-thrift-license.txt in the Thrift distribution for
+ * details.
+ */
+
+using System;
+
+namespace Thrift.Protocol
+{
+    public class TProtocolException : TException
+    {
+        public const int UNKNOWN = 0;
+        public const int INVALID_DATA = 1;
+        public const int NEGATIVE_SIZE = 2;
+        public const int SIZE_LIMIT = 3;
+        public const int BAD_VERSION = 4;
+        public const int NOT_IMPLEMENTED = 5;
+        public const int DEPTH_LIMIT = 6;
+
+        protected int type_ = UNKNOWN;
+
+        public TProtocolException()
+            : base()
+        {
+        }
+
+        public TProtocolException(int type, Exception inner = null)
+            : base(string.Empty, inner)
+        {
+            type_ = type;
+        }
+
+        public TProtocolException(int type, string message, Exception inner = null)
+            : base(message, inner)
+        {
+            type_ = type;
+        }
+
+        public TProtocolException(string message, Exception inner = null)
+            : base(message, inner)
+        {
+        }
+
+        public int getType()
+        {
+            return type_;
+        }
+    }
+}