TODO

* Test on more platforms.  Development has primarily been on Linux and some
  attempts have been made on FreeBSD, OpenBSD, and OS X.

* Display status in the executor using pstack/dtract/gstack.

* Display elapsed time of currently running query.

* Display SQL statement type currently executing, i.e. SELECT, UPDATE,
  VACUUM, etc.

* Display summary statistics for average query cpu time, average query elapsed
  time, etc.

* Display summary statistics for locks such as total number of granted locks,
  total number of ungranted locks, etc.

* Make new TPS and i/o activity and disk space usage work on remote
  connections.

* Add warning when user running pg_top does not have OS privileges to view i/o
  statistics.  /proc/*/io may only be readable by process owner.

* Add warning when user i/o stats are not avaialble from OS. (Linux)