Support for type destructuring

TypeScript Version: 2.1.4

Code

import { MyNamespace } from 'my-package';

// importing Class objects:
const { NavLink, NavGroup } = MyNamespace; // VALID

// if we want the types as well:
type { NavLink, NavGroup } = MyNamespace; // NOT VALID

// So we have to go manual: 
type NavLink = MyNamespace.NavLink;  // VALID
type NavGroup = MyNamespace.NavLink;  // VALID

Expected behavior:
Being able to use destructuring for types same as we use for objects.

Actual behavior:
Can only use destructuring for objects.

The issue provides no repository file, test, or entry point to begin from. Start by reproducing the TypeScript 2.1.4 example and then trace how object destructuring and type aliases are parsed and checked. Done means type destructuring works for the shown namespace example with appropriate compiler coverage and no regression to object destructuring.