Streamlined #1.

Following advice from @jdoliner, did some better string-or-list
checking.  Decided to import requests as it made the spider run 4 - 6
times faster [on my PC] and use that to get html.  Tried to make the
example make more sense, but still needs documentation.

to do: almost everything.  make more extendable [n-th connections from
any base_url --- warn users if more than 500 items have been processed?