[exim] EXPERIMENTAL_TPDA

Users of EXPERIMENTAL_TPDA be warned: just pushed is an
incompatible change to the feature. You *will* need to
rewrite the relevant portions of your exim.conf files.

Please read the experimental-spec.txt file for further
information, or mail me. Comments, further feature
requests, cursing - all welcome.

Anyone with a standard build should not be affected.
--
Cheers,
Jeremy