Add a README so GitHub's WebIF shuts up.

Basic README disclaiming any fitness, suitability or (ha ha) reliability of the Python source contained herein.  This is a public repo, so one assumes the "content" here has an open license (maybe the DWTFYWL?), but no license terms are explicitly stated.  DWTFYW, and I promise I won't sue provided you don't use anything I put here to lessen the biological success of those I care about.