Discussion: using directive on concrete types

[alrz]

Currently using directives may cause possible breaking type binding changes if a type with the same name is added to a parent namespace, One could use type aliases to avoid just that,

using Action = System.Action;
using Action<T> = System.Action<T>;

We could make it more straightforward to allow concrete types directly in using directives (like Java imports).

using System.Action;
using System.Action<>;

Rel: #90