Hide useless object members from intellisense

[vbfox]

At least GetHashCode, GetType and the non-generic Equals should be hidden.

Examples :

• http://blogs.clariusconsulting.net/kzu/how-to-hide-system-object-members-from-your-interfaces/
• https://github.com/NancyFx/Nancy/blob/master/src/Nancy/IHideObjectMembers.cs