pg_autovacuum vacuum cost variables patch

Hello, as per some discussion on the lists a few days ago, I am
submitting this patch against the CVS version of pg_autovacuum.

This patch adds 5 new command line options to pg_autovacuum that
directly correspond to the 5 new vacuum cost GUC variables in 8.0. I
have done some simple testing and this patch works Ok on my FC3 box.

Two questions:
1) It is my understanding that these new GUC vars only effect vacuum.
That is they do NOT have any effect on an analyze command right? (I ask
since I'm only setting the vars before I issue a vacuum command)
2) Does anyone have any better suggestions for the letters used for the
new pg_autovacuum command line args? Nothing obvious came to mind, so I
just basically picked at random resulting in this:
-c vacuum_cost_delay
-C vacuum_cost_page_hit
-m vacuum_cost_page_miss
-n vacuum_cost_page_dirty
-N vacuum_cost_limit
Any better ideas?

Please review and if deemed accecptable, please apply to CVS HEAD.

Thanks,

Matthew O'Connor