As of logbook 0.10.0, logbook no longer installs a default handler,
which means that if the application doesn't install one, log messages
disappear into the ether.
Therefore, all of our scripts with `__main__` endpoints need to push a
`logbook.StderrHandler` if they're not already pushing some other
handler.
on the number of per-tick update that occur since they were duplicated
per each PerformancePeriod. Also opens up the path to cythonizing the
entire object
Jonathan Kamens