jsImport - use ES6 imports in Haxe

With -lib jsImport you can decorate any extern class with @:js.import like so:

• @:js.import(@star './some/path.js') extern class Foo {} becomes import * as Foo from './some/path.js'
• @:js.import(@default './some/path.js') extern class Foo {} becomes import Foo from './some/path.js'
• @:js.import('./some/path.js') extern class Foo {} becomes import { Foo } from './some/path.js'
• @:js.import('./some/path.js', 'SomeName') extern class Foo {} becomes import { SomeName } from './some/path.js'