Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Core.Domain/Interfaces/ICalendarItem.cs

@@ -0,0 +1,14 @@
+using System;
+using Itenso.TimePeriod;
+
+namespace Wino.Core.Domain.Interfaces
+{
+    public interface ICalendarItem
+    {
+        string Name { get; }
+        Guid Id { get; }
+        DateTime StartTime { get; }
+        DateTime EndTime { get; }
+        TimeRange Period { get; }
+    }
+}