[WIP] showing index maintenance on EXPLAIN

Hi,

This patch implements $subject only when ANALYZE and VERBOSE are on.
I made it that way because for years nobody seemed interested in this
info (at least no one did it) so i decided that maybe is to much
information for most people (actually btree indexes are normally very
fast).

But because we have GiST and GIN this became an interested piece of
data (there are other cases even when using btree).

Current patch doesn't have docs yet i will add them soon.

--
Jaime Casanova www.2ndQuadrant.com
Professional PostgreSQL: Soporte 24x7 y capacitación
Phone: +593 4 5107566 Cell: +593 987171157