[dotnet] Add dotnet projects and examples

+ Sitemap generator I created while learning the dispose pattern
+ Testing project for learning general C#

dotnet/sitemap/SiteMapLibrary/XmlManager.cs

@@ -0,0 +1,59 @@
+using System.Xml;
+
+namespace SiteMapLibrary;
+
+public class XmlManager
+{
+  private XmlDocument XmlDocument { get; set; }
+  private XmlDeclaration XmlDeclaration { get; set; } 
+  private XmlElement XmlUrlset { get; set; }
+  private string Path { get; set; }
+
+  public XmlManager(string path,
+    string version="1.0", string encoding="utf-8", string standalone="")
+  {
+    XmlDocument = new XmlDocument();
+    XmlDeclaration = XmlDocument.CreateXmlDeclaration(version, encoding, standalone);
+    XmlDocument.AppendChild(XmlDeclaration);
+    XmlUrlset = XmlDocument.CreateElement("urlset");
+    XmlDocument.AppendChild(XmlUrlset);
+    Path = path;
+  }
+
+  ~XmlManager()
+  {
+    Save();
+  }
+  
+  public void AddUrl(string url)
+  {
+    XmlElement newUrl = XmlDocument.CreateElement("url");
+    XmlUrlset.AppendChild(newUrl);
+    XmlElement newLoc = XmlDocument.CreateElement("loc");
+    newLoc.InnerText = url;
+    newUrl.AppendChild(newLoc);
+    var lastmod = XmlDocument.CreateElement("lastmod");
+    lastmod.InnerText = DateTime.Now.Year.ToString() 
+                        + '-' + DateTime.Now.Month.ToString()
+                        + '-' + DateTime.Now.Day;
+    newUrl.AppendChild(lastmod);
+    var changeFreq = XmlDocument.CreateElement("changefreq");
+    changeFreq.InnerText = "daily";
+    newUrl.AppendChild(changeFreq);
+    var priority = XmlDocument.CreateElement("priority");
+    priority.InnerText = "0.5";
+    newUrl.AppendChild(priority);
+  }
+  
+  public void Save()
+  {
+    if (Path == "Console.Out")
+    {
+      XmlDocument.Save(Console.Out);
+    }
+    else
+    {
+      XmlDocument.Save(Path);
+    }
+  }
+}