Added write support for binary files!

Holy cow, this took a lot of work. I think I may need to do a few more
things before I consider this a 1.0 release, but I'm glad to have
finally overcome this hurdle!

Tree/Instance.cs

@@ -18,17 +18,23 @@ namespace RobloxFiles
         private Dictionary<string, Property> props = new Dictionary<string, Property>();
         public IReadOnlyDictionary<string, Property> Properties => props;
 
-        private List<Instance> Children = new List<Instance>();
+        protected List<Instance> Children = new List<Instance>();
         private Instance parent;
 
         /// <summary>The name of this Instance, if a Name property is defined.</summary>
         public override string ToString() => Name;
 
-        /// <summary>A unique identifier for this instance when being serialized as XML.</summary>
-        public string XmlReferent { get; internal set; }
+        /// <summary>A unique identifier for this instance when being serialized.</summary>
+        public string Referent { get; internal set; }
 
         /// <summary>Indicates whether the parent of this object is locked.</summary>
-        public bool ParentLocked { get; protected set; }
+        public bool ParentLocked { get; internal set; }
+
+        /// <summary>Indicates whether this Instance is marked as a Service in the binary file format.</summary>
+        public bool IsService { get; internal set; }
+
+        /// <summary>If this instance is a service, this indicates whether the service should be loaded via GetService when Roblox loads the place file.</summary>
+        public bool IsRootedService { get; internal set; }
 
         /// <summary>Indicates whether this object should be serialized.</summary>
         public bool Archivable = true;

Tree/Property.cs

@@ -1,4 +1,6 @@
 using System;
+
+using RobloxFiles.BinaryFormat;
 using RobloxFiles.BinaryFormat.Chunks;
 
 namespace RobloxFiles
@@ -47,6 +49,8 @@ namespace RobloxFiles
         public string XmlToken = "";
         public byte[] RawBuffer { get; internal set; }
 
+        internal BinaryRobloxFileWriter CurrentWriter;
+
         public bool HasRawBuffer
         {
             get
@@ -83,10 +87,9 @@ namespace RobloxFiles
 
         public Property(string name = "", PropertyType type = PropertyType.Unknown, Instance instance = null)
         {
+            Instance = instance;
             Name = name;
             Type = type;
-
-            Instance = instance;
         }
 
         public Property(Instance instance, PROP property)
@@ -116,5 +119,28 @@ namespace RobloxFiles
 
             return string.Join(" ", typeName, Name, '=', valueLabel);
         }
+
+        public T CastValue<T>()
+        {
+            T result;
+
+            if (Value is T)
+                result = (T)Value;
+            else
+                result = default(T);
+
+            return result;
+        }
+
+        internal void WriteValue<T>() where T : struct
+        {
+            if (CurrentWriter == null)
+                throw new Exception("Property.CurrentWriter must be set to use WriteValue<T>");
+
+            T value = CastValue<T>();
+
+            byte[] bytes = BinaryRobloxFileWriter.GetBytes(value);
+            CurrentWriter.Write(bytes);
+        }
     }
 }