In various places, we build messages using `Sprintf` before passing them
to `Notice()`.
If we let `Notice()` do string formatting, we run the chance of having
it try to format our already-preformatted text. If our text includes
format references (e.g. `%s`), it would cause a problem (`%s(MISSING)`).
One way to trigger it is to change the bot prefix from `!pm` to `%pm`.
Doing so, `sendHelp()` would create some help message which contains
`%pm` references. `Notice()` would then try to process them as well,
leading to a bunch of `%!p(MISSING)m` in the final text.