Added MultipleDeck which can be used in place of the old QuadDeck, converted cards from classes to records as it is useful to have default equality checks.

src/Nadeko.Econ/Deck/Regular/RegularDeck.cs

@@ -2,4 +2,14 @@
 
 public sealed class RegularDeck : NewDeck<RegularCard, RegularSuit, RegularValue>
 {
+    public RegularDeck()
+    {
+        foreach (var suit in _suits)
+        {
+            foreach (var val in _values)
+            {
+                _cards.AddLast((RegularCard)Activator.CreateInstance(typeof(RegularCard), suit, val)!);
+            }
+        }
+    }
 }