Add skeleton mapping attribute

SabreTools.Models/MappingAttribute.cs

@@ -0,0 +1,27 @@
+using System;
+
+namespace SabreTools.Models
+{
+    /// <summary>
+    /// Represents a mapping to internal models
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Field)]
+    public class MappingAttribute : Attribute
+    {
+        /// <summary>
+        /// Internal name for the mapping
+        /// </summary>
+        public string Name { get; set; }
+        
+        /// <summary>
+        /// Determines if the mapped value is required or not
+        /// </summary>
+        public bool Required { get; set; }
+        
+        public MappingAttribute(string name, bool required = false)
+        {
+            this.Name = name;
+            this.Required = required;
+        }
+    }
+}