passthrough mode will no longer waste memory when the input file is seekable.

[Matthias Andree]

Hi,

the considerable amount of checkins has consisted of preparations (and
their revisions) and changes to main.c to allow bogofilter -p read the
passthrough input from disk when the input is seekable (e. g. bogofilter
-pe <email) and making bogofilter's memory consumption more
controllable.

David, the merge is now complete.

Cheers,

-- 
Matthias Andree