default resource limits

The discussion was a bit inconclusive last time, so I would like to
renew my proposal for more generous default resource limits.

Nearly everyone seems to agree that the default for max_fsm_pages is
woefully low, so I would like to have the default for this set
unconditionally to 200,000 rather than 20,000. The cost would be just
over 1Mb of shared memory, if the docs are correct. Alternatively, we
could put this into the mix that is calculated by initdb, scaling it
linearly with shared_buffers (but with the default still at 200,000).

I would also like to propose a more modest increase in max_connections
and shared_buffers by a factor of 3. This number is picked with some
caution, and is intended to ensure that a) we don't eat all the
resources on a modestly resourced machine, and b) we can accomodate 1
connection per apache child in a typical (unix) apache configuration. If
we were slightly less conservative, we'd at least take default
max_connections to 400, which is the maximum number of apache threads on
Windows, in the default configuration.)

Since the time when these defaults were set, the price of memory has
plummeted, and the typical memory population of an entry level machine
has roughly quadrupled, from my observation, so it seems to me that by
revising these limits we are just adjusting to the new reality.

cheers

andrew