Weighing: Add ICommandScale and IEventScale

Elwig/Helpers/Weighing/IEventScale.cs

@@ -0,0 +1,8 @@
+namespace Elwig.Helpers.Weighing {
+    /// <summary>
+    /// Interface for controlling a a scale which automatically sends weighing updates
+    /// </summary>
+    public interface IEventScale : IScale {
+
+    }
+}