Patch for pop3-file bug

[Serge Knystautas <se...@lokitech.com>]

The change is very distinct from the rest of the code, so I've just 
attached it so people can test it if they like.

It's almost entirely new files... I copied over the underlying file 
repository code from Avalon into a new package in James 
(org.apache.james.mailrepository.filepair), removed the numbering, and 
added logic during initialization to unnumber files as best it can. 
It's really a pretty minimal change as everyone suspected.  It logs all 
the file renaming it does (successful and unsuccessful).

So attached is the very small diff to james-config.xml that changes the 
two places where the underlying file repository implementation was 
specified, and a zip of the source code to put into 
src/java/org/apache/james/mailrepository/filepair.

To test, I was using the old file repositories, would deliver messages, 
add accounts, restart, repeat this cycle a few times so messages would 
get lost several times.  Then I changed config to point to the new 
implementation, and all those lost messages are found.  Hopefully though 
people with much larger installations can test to make sure the 
migration works for them.

-- 
Serge Knystautas
Loki Technologies
http://www.lokitech.com/