I notice we seem to have a typo in the SAM_ status codes (they say
IMMEDIATE where they mean INTERMEDIATE).

I've also introduced a new macro who's job is to return true if any of
the possible good return codes is found.  This means

SAM_STAT_GOOD
SAM_STAT_INTERMEDIATE
SAM_STAT_INTERMEDIATE_CONDITION_MET

and for now

SAM_STAT_COMMAND_TERMINATED

By and large, this is currently irrelevant to us, since we don't use
linked commands and I've never met a device using COMMAND TERMINATED,
but it may help us in the future.