Update to 2.71

Upstream changes:
2.71    2023-04-05

- The docs for the Screen output were never updated after the changes in 2.50,
  when it reverted back to using STDOUT or STDERR directly. This led to a lot
  of the docs being confusing and wrong. Reported by @mauke. GH #65, #66, and
  #67.

(wen)