this proved easier to understand, also because it makes the macro
registry's scope more explicit

also tweaked `#renderView`'s signature to avoid non-descriptive boolean

before:

    import renderer from "complate-stream";
    …
    let { renderView, registerView } = renderer(doctype);
    …
    registerView(…);
    renderView(view, params, stream, fragment, callback);

after:

    import Renderer from "complate-stream";
    …
    let renderer = new Renderer(doctype);
    …
    renderer.registerView(…);
    renderer.renderView(view, params, stream, { fragment }, callback);

in the process, updated dependencies