First limit 1
I'd like to preserve the behavior where multiple calls to `first()` does not yield multiple queries. I _do_ agree, though, that there is benefit in applying a limit and that a second `peek()` method might more correctly. I've gone ahead and implemented this in a separate patch. You can compare notes to see how I've done this a bit differently: eeb6d4d727da8536906a00c490f94352465e90bb
 +1

for possible future inclusion (not 2.8.2) regarding https://github.com/coleifer/peewee/issues/959 or if anyone else wants to pull it into their forks.
