Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Core.Domain/Enums/CalendarLoadDirection.cs

@@ -0,0 +1,12 @@
+namespace Wino.Core.Domain.Enums
+{
+    /// <summary>
+    /// Which way in time to load more data for calendar.
+    /// </summary>
+    public enum CalendarLoadDirection
+    {
+        Replace,
+        Previous,
+        Next
+    }
+}