gendoc: make commnd __doc__ and extension __doc__ as translatable Before this patch, commnd __doc__ and extension __doc__ are not translatable. But other messages, like doc of helptalbe, section headers, are translatable. This patch makes commnd __doc__ and extension __doc__ translatable.

blackbox: fix blackbox causing exceptions in tests In the tests some scripts call reposetup with the base ui instead of the one the extensions have modified. This causes an exception in blackbox.reposetup since it expected a method to be there. So I just check for it first. This only happened when the blackbox extension was enabled during tests.

blackbox: fix recording exit codes (issue3938) Previously the blackbox wrapped runcommand, but this failed to see the error codes that were created if an exception occurred. I moved that logging to now wrap _runcatch, so it can observe and log the actual error code (such as when a user ctrl+c's during a command). Updated the tests as well. Tested the change by running all the tests with the blackbox extension enabled and verifying nothing broke (aside from things that printed what extensions were enabeld). The progress tests are affected by calls to time.time() so they needed to be updated to pass.