Added db4o.

Added guards against most problematic areas.

NzbDrone.Core/Datastore/DbProviderFactory.cs

@@ -1,6 +1,10 @@
-using System;
+using System;
 using System.Data.Common;
 using System.Data.SqlServerCe;
+using Db4objects.Db4o;
+using Db4objects.Db4o.IO;
+using Db4objects.Db4o.Internal;
+using Db4objects.Db4o.Internal.Config;
 using StackExchange.Profiling;
 using StackExchange.Profiling.Data;
 
@@ -23,4 +27,23 @@ namespace NzbDrone.Core.Datastore
             return connection;
         }
     }
+
+
+    public class ObjectDbSessionFactory
+    {
+        public IObjectDbSession Create(IStorage storage = null)
+        {
+            if (storage == null)
+            {
+                storage = new FileStorage();
+            }
+
+            var config = Db4oEmbedded.NewConfiguration();
+            config.File.Storage = storage;
+           
+
+            var objectContainer = Db4oEmbedded.OpenFile(config, "nzbdrone.db4o");
+            return new ObjectDbSession((ObjectContainerBase)objectContainer);
+        }
+    }
 }