[Exim] Planning for Exim 4

I have re-instated the planning document at

ftp://ftp.csx.cam.ac.uk/pub/software/email/exim/Exim4Plan.html

I have revised it in the light of previous comments and what has already
been implemented for Exim 4. It was done fairly hastily, so the
information is brief, but I hope it is useful.

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.