Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Calendar/Args/TimelineCellUnselectedArgs.cs

@@ -0,0 +1,9 @@
+using System;
+
+namespace Wino.Calendar.Args
+{
+    /// <summary>
+    /// When selected timeline cell is unselected.
+    /// </summary>
+    public class TimelineCellUnselectedArgs : EventArgs { }
+}