Fix symmetry violation of ValueObject comparison

[teheran]

Comparing two incomparable objects in this way can lead to unpredictable results.

    private int CompareComponents(object object1, object object2)
    {
        ...
        **return object1.Equals(object2) ? 0 : -1;**
    }

Expected if (object1 > object2) then (object2 < object1)

To prevent comparison of non-comparable components of VO it is proposed to change signature of ValueObject.GetEqualityComponents abstract method:

--protected abstract IEnumerable<object> GetEqualityComponents();
++protected abstract IEnumerable<IComparable> GetEqualityComponents();

[vkhorikov]

Thanks much. Will publish this shortly.