New smtp.py

[chris]

Dougal Scott has submitted a much more powerful version of smtp.py. Dougal's comments:

I've rewritten huge slabs of the lib/common/Directives/smtp.py to do a full smtp transaction - as opposed to the previous one which just waited for the '220 hello' (This has bitten us - hence I wrote this). The new on has timings of every step, access to the full transaction log, and including the ability to do authenticated smtp. This should be backwards compatible with the old one. This has alos only undergone rudimentary testing.

[chris]

smtp.py submitted by Dougal Scott.