fetch-dom

`fetch-dom' is the main entry function in this package.  It will
try to fetch URL by using three methods:

1) First try to fetch URL using the normal, fast method.

2) If this fails, use Selenium headless.  This involves spinning up
   a web browser and then dumping the resulting DOM.

3) If this fails, spin up Selenium and a web browser window.  This
   will allow the user to click around a bit, answering any
   challenges.

In 2) and 3), `fetch-dom' will save and reuse cookies, so that
hopefully 3) doesn't happen as much, and 1) and 2) will be
successful more often.