Removed NioTSO client and server

- NioTSO client isn't needed because we're using RayLib
- Added FreeSO's API server to handle most backend operations

server/tso.common/Utils/IXMLEntity.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Xml;
+
+namespace FSO.Common.Utils
+{
+    public interface IXMLEntity
+    {
+        XmlElement Serialize(XmlDocument doc);
+        void Parse(XmlElement element);
+    }
+
+    public static class XMLUtils
+    {
+        public static T Parse<T>(string data) where T : IXMLEntity
+        {
+            var doc = new XmlDocument();
+            doc.LoadXml(data);
+
+            T result = (T)Activator.CreateInstance(typeof(T));
+            result.Parse((XmlElement)doc.FirstChild);
+            return result;
+        }
+
+        public static void AppendTextNode(this XmlElement e, string nodeName, string value)
+        {
+            var node = e.OwnerDocument.CreateElement(nodeName);
+            node.AppendChild(e.OwnerDocument.CreateTextNode(value));
+            e.AppendChild(node);
+        }
+
+        public static string ReadTextNode(this XmlElement e, string nodeName)
+        {
+            foreach (XmlElement child in e.ChildNodes)
+            {
+                if (child.Name == nodeName && child.FirstChild != null)
+                {
+                    return child.FirstChild?.Value;
+                }
+            }
+            return null;
+        }
+    }
+}