Merge branch 'better-deferred-api-13' into trial-logs-69
Start implementation of redirecting Eliot logs to Twisted.
Tests for actual output of Twisted log messages.
Don't bother with _ parameter names.
Add default global impact to redirectLogsForTrial.
Document the new API.
Merge remote-tracking branch 'refs/remotes/origin/master' into trial-logs-69
Document new API.
Address review comment: Missing word.
Address review comment: Move FakeSys into separate module of testing utils.
Address review comment: Use @type.
Address review comment: Fail more informatively.
Address review comments: We can do better trial detection.
Address review comments: Better test coverage for trial detection.
Address review comment: Better explanation of return result.
Address review comment: % and tuple, like peanut butter and jam.
Make redirectLogsForTrial idempotent, and to test that more easily
refactor redirectLogsForTrial into a class.
Add reference to thread-safety issue.
Document idempotency.
Fix pyflakes error.