Support Guid serialization

NAPS2.Internals/Serialization/XmlSerializer.cs

@@ -50,6 +50,7 @@ public abstract class XmlSerializer
         { typeof(ImmutableList<>), new XmlTypeInfo { CustomSerializer = new ImmutableListSerializer() } },
         { typeof(ImmutableHashSet<>), new XmlTypeInfo { CustomSerializer = new ImmutableHashSetSerializer() } },
         { typeof(DateTime), new XmlTypeInfo { CustomSerializer = new DateTimeSerializer() } },
+        { typeof(Guid), new XmlTypeInfo { CustomSerializer = new GuidSerializer() } },
         { typeof(Nullable<>), new XmlTypeInfo { CustomSerializer = new NullableSerializer() } },
     };
 
@@ -652,6 +653,19 @@ public abstract class XmlSerializer
         }
     }
 
+    protected class GuidSerializer : CustomXmlSerializer<Guid>
+    {
+        protected override void Serialize(Guid obj, XElement element)
+        {
+            element.Value = obj.ToString();
+        }
+
+        protected override Guid Deserialize(XElement element)
+        {
+            return Guid.Parse(element.Value);
+        }
+    }
+
     protected class NullableSerializer : CustomXmlSerializer
     {
         public override void SerializeObject(object obj, XElement element, Type type)