Last call: connection pooling patch

I've finished up my work on connection pooling, patch is here:

Please try it out, comment, etc. and give +1s if you want. Any comments on default pool size (5) or default wait timeout (5 seconds)?

Note that this is probably not the last word -- the patch still needs to be battle-tested, but we expect that to be done once the patch gets merged into edge and any necessary fixes will follow.

Cheers, /Nick