If you are upgrading from pre-v0.3.0, make sure to check out the CHANGES
file.  ifile has undergone a complete rewrite since then.

If you upgrading from a version before 0.2.3, you should take a look at
"knowledge_base.perl".  This is a script which will compile an .idata file
from ALL of the messages you currently have stored.  In most cases, this
will result in much improved filtering (yet a somewhat larger .idata file).

During the transition between v0.1.2 of ifile and v0.2.0, I have changed the
format which is used to store the information used for e-mail classification.

If you are upgrading from any v0.1.x version, each user which will be using
this new version of ifile will need to run the script './convert.perl'.  The
script will detect the user's home directory, back up the old data file and
create a newly formatted data file with the information from the old data
file.

