Extended VersionHistoryIndex to pull versions from all sources

In theory, `Attributes` should be the most authoritative place for accessing the `VersionHistory` since the OnTopic Editor will, at minimum, write a `LastModified` and `LastModifiedBy` attribute for every `Save()`. If a topic is saved programmatically, or an implementation disables the `LastModified` attributes, however, then this won't necessarily be the case.

This is especially a concern now that `Relationships` and `TopicReferences` are both versioned. We don't want updates that don't impact `Attributes` to be excluded from the `VersionHistoryIndex`—and, thus, not available for `Rollback()` in the OnTopic Editor.

This update to the `VersionHistoryIndex` addresses this by pulling versions not just from `Attributes`, but also from `ExtendedAttributes`, `Relationships`, and `TopicReferences`. This resolves #78.

Author: JeremyCaney

OnTopic.Data.Sql.Database/Views/VersionHistoryIndex.sql

@@ -18,9 +18,31 @@ AS (
 	  PARTITION BY		TopicID
 	  ORDER BY		Version DESC
 	)
-  FROM	[dbo].[Attributes]
-  GROUP BY	TopicID,
+  FROM (
+    SELECT	TopicID,
 	Version
+    FROM	[dbo].[Attributes]
+    GROUP BY	TopicID,
+	Version
+    UNION
+    SELECT	TopicID,
+	Version
+    FROM	[dbo].[ExtendedAttributes]
+    GROUP BY	TopicID,
+	Version
+    UNION
+    SELECT	Source_TopicID AS TopicID,
+	Version
+    FROM	[dbo].[TopicReferences]
+    GROUP BY	Source_TopicID,
+	Version
+    UNION
+    SELECT	Source_TopicID AS TopicID,
+	Version
+    FROM	[dbo].[Relationships]
+    GROUP BY	Source_TopicID,
+	Version
+  ) AS	VersionList
 )
 SELECT	Versions.TopicId,
 	Version