Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Core.Domain/Entities/Calendar/AccountCalendar.cs

@@ -0,0 +1,16 @@
+using System;
+using SQLite;
+
+namespace Wino.Core.Domain.Entities.Calendar
+{
+    public class AccountCalendar
+    {
+        [PrimaryKey]
+        public Guid Id { get; set; }
+
+        public Guid AccountId { get; set; }
+        public string Name { get; set; }
+        public string ColorHex { get; set; }
+        public string TimeZoneId { get; set; }
+    }
+}