Fix double declaration of namespaces problem

Author: alex-kulakov

Orm/Xtensive.Orm/Orm/Model/TypeInfo.cs

@@ -6,7 +6,6 @@
 
 using System;
 using System.Collections;
-using System.Collections.Immutable;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Collections.ObjectModel;
@@ -19,7 +18,6 @@
 using Xtensive.Tuples;
 using Xtensive.Tuples.Transform;
 using Tuple = Xtensive.Tuples.Tuple;
-using JetBrains.Annotations;
 
 namespace Xtensive.Orm.Model
 {

Orm/Xtensive.Orm/Reflection/AttributeHelper.cs

@@ -12,7 +12,6 @@
 using Xtensive.Core;
 using AttributesKey = System.ValueTuple<System.Reflection.MemberInfo, System.Type, Xtensive.Reflection.AttributeSearchOptions>;
 using PerAttributeKey = System.ValueTuple<System.Reflection.MemberInfo, Xtensive.Reflection.AttributeSearchOptions>;
-using Xtensive.Core;
 
 namespace Xtensive.Reflection
 {