[Critical] Fixed issues with Topic construction

While the `id` value is optional on the constructor, `Activator.CreateInstance()` doesn't honor that; to function, an `id` value _must_ be provided. In addition, before properties can be set, the `Attributes` property must be initialized.

Author: JeremyCaney

Ignia.Topics/Topic.cs

@@ -55,6 +55,15 @@ public class Topic {
     /// <returns>A strongly-typed instance of the <see cref="Topic"/> class based on the target content type.</returns>
     public Topic(string key, string contentType, Topic parent, int id = -1) {
 
+      /*----------------------------------------------------------------------------------------------------------------------
+      | Set relationships
+      \---------------------------------------------------------------------------------------------------------------------*/
+      Children                  = new TopicCollection(this);
+      Attributes                = new AttributeValueCollection(this);
+      IncomingRelationships     = new RelatedTopicCollection(this, true);
+      Relationships             = new RelatedTopicCollection(this, false);
+      VersionHistory            = new List<DateTime>();
+
       /*----------------------------------------------------------------------------------------------------------------------
       | Set core properties
       \---------------------------------------------------------------------------------------------------------------------*/
@@ -74,15 +83,6 @@ public Topic(string key, string contentType, Topic parent, int id = -1) {
         }
       }
 
-      /*----------------------------------------------------------------------------------------------------------------------
-      | Set relationships
-      \---------------------------------------------------------------------------------------------------------------------*/
-      Children                  = new TopicCollection(this);
-      Attributes                = new AttributeValueCollection(this);
-      IncomingRelationships     = new RelatedTopicCollection(this, true);
-      Relationships             = new RelatedTopicCollection(this, false);
-      VersionHistory            = new List<DateTime>();
-
     }
 
     #region Core Properties

Ignia.Topics/TopicFactory.cs

@@ -148,7 +148,7 @@ public static Topic Create(string key, string contentType, Topic parent = null)
       /*----------------------------------------------------------------------------------------------------------------------
       | Identify the appropriate topic
       \---------------------------------------------------------------------------------------------------------------------*/
-      var topic = (Topic)Activator.CreateInstance(targetType, key, contentType, parent);
+      var topic = (Topic)Activator.CreateInstance(targetType, key, contentType, parent, -1);
 
       /*----------------------------------------------------------------------------------------------------------------------
       | Return the topic