Handle dayOfWeek+dayOfMonth the same as vixiecron

    crontab(5) says
    > The day of a command's execution can be specified by two fields - day of
    > month, and day of week. If both fields are restricted (ie, aren't *),
    > the command will be run when either field matches the current time.

The current behaviour is to require both fields to match. Since there are no
tests covering this case, I assume it wasn't considered in development.