#8 low-latency enhancement

[John V Sichi]

For result sets that take a long time to compute, it's
useful to be able to see the first few rows as they are
produced (rather than waiting for the entire result
set). I propose

!set incremental on

to enter low-latency mode. Of course, in this mode, we
can't optimize display properties such as the maximum
column width, so instead we have to rely on metadata
(meaning the bounds won't be as tight as when we rely
on the actual data).