title: skip library check only in node_modules
body: <p>There are several questions about disabling errors in mistyped <code>node_modules</code> (e.g., <a href="https://stackoverflow.com/questions/49906424/rxjs5-typescript-typings-fail/49912245#49912245">this one</a>, or <a href="https://stackoverflow.com/questions/40547903/tsconfig-js-exclude-property-not-working-when-import-modules-is-used/40563012#40563012">this one</a>), but they all involve using the <code>skipLibCheck</code> compiler flag.</p>
  
  <p>Are there other solutions to this problem (e.g., using <code>include</code> or  <code>exclude</code>)? I have a couple of hand-written <code>.d.ts</code> files (stricter types than available on DefinitelyTyped) that I'd like to type check, so the wholesale disabling of typechecking on these files is not appealing.</p>