Opal 1.0

Dear Opalists of the world, the time has come, 1.0 has been released!This is, of course, a really important milestone, one that I've been waiting on for about seven years. I started advocating for releasing version 1.0 back in 2012 when Opal was still at version 0.3. After all, at that time I already had code in production, and according to Semver (which by then was still a new thing) that's one of the criteria for releasing 1.0:.