changed framework to dotnet6

Experimental/Tester.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Diagnostics;
+
+namespace DTLib.Experimental
+{
+    public static class Tester
+    {
+        public static void LogOperationTime(string op_name, int repeats, Action operation)
+        {
+            Stopwatch clock = new();
+            clock.Start();
+            for (int i = 0; i < repeats; i++)
+                operation();
+            clock.Stop();
+            PublicLog.LogNoTime("c",$"operation {op_name} took {clock.ElapsedTicks / repeats} ticks\n");
+        }
+    }
+}