Start creating Dictionary-based internal models

SabreTools.Models/Internal/Condition.cs

@@ -0,0 +1,27 @@
+using System.Xml.Serialization;
+using Newtonsoft.Json;
+
+namespace SabreTools.Models.Internal
+{
+    [JsonObject("condition"), XmlRoot("condition")]
+    public class Condition : DatItem
+    {
+        #region Keys
+
+        /// <remarks>string</remarks>
+        public const string ValueKey = "clock";
+
+        /// <remarks>string</remarks>
+        public const string MaskKey = "mask";
+
+        /// <remarks>(eq|ne|gt|le|lt|ge)</remarks>
+        public const string RelationKey = "relation";
+
+        /// <remarks>string</remarks>
+        public const string TagKey = "tag";
+
+        #endregion
+
+        public Condition() => Type = ItemType.Condition;
+    }
+}