Got rid of a lot of no longer needed work in Lookup.add(). Minimized

the number of explicit session.flush()s. Fixed several places that
were throwing uninformative exceptions.


git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/BRANCHES/WCM-DEV2/root@3227 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/avm/RepositoryImpl.java

@@ -131,7 +131,7 @@ class RepositoryImpl implements Repository, Serializable
         // If the root isn't new, we can't take a snapshot since nothing has changed.
         if (!fRoot.getIsNew())
         {
-            // TODO Silently return for now.
+            throw new AVMExistsException("Already snapshotted.");
         }
         // Clear out the new nodes.
         Query query =