Export: Refactor interfaces and classes

Elwig/Helpers/Billing/Transaction.cs

@@ -0,0 +1,14 @@
+using Elwig.Models;
+
+namespace Elwig.Helpers.Billing {
+    public class Transaction {
+
+        public readonly Member Member;
+        public readonly int AmountCent;
+
+        public Transaction(Member m, decimal amount) {
+            Member = m;
+            AmountCent = (int)(amount * 100);
+        }
+    }
+}