Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Calendar/Models/CalendarItemMeasurement.cs

@@ -0,0 +1,17 @@
+namespace Wino.Calendar.Models
+{
+    public struct CalendarItemMeasurement
+    {
+        // Where to start?
+        public double Left { get; set; }
+
+        // Extend until where?
+        public double Right { get; set; }
+
+        public CalendarItemMeasurement(double left, double right)
+        {
+            Left = left;
+            Right = right;
+        }
+    }
+}