Currently, hspace can only output a machine-readable format that
(while detailed) is hard to parse quickly by people. This patch adds
(and enables by default) a human-readable output that shows the most
important metrics in a simple format.

Most of the work of the patch is in moving the display of various
metrics from the 'main' function to separate functions, each of which
can output either a machine or human intended format.

The patch also corrects a bug in the CPU efficiency display: before,
the efficiency was computed as instance virtual CPUs divided by total
physical CPUs, which is almost always supra-unitary. More correct is
to divide by the total virtual CPUs, which shows a more meaningful
number (when the p-to-v CPU ratio has been defined correctly).

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>