[imp] Monthly maintenance still not working properly - folder name encoding issues

[Tero Matinlassi]

IMP's monthly maintenance is still not working properly: the renamed 
sent-mail folder name is wrong because the month name isn't encoded in 
UTF-7.

Also as a sidenote, the maintenance screen still shows folder path and 
encoded folder names instead of folder name only and in decoded form.

This is with RELENG, but probably with HEAD too, since 
rename_sentmail_monthly.php doesn't differ a much between the branches.

Here's a screenshot sent by one user of ours; it's in Finnish but you 
might get the idea: https://mail.edu.vantaa.fi/horde-dev/maintenance-
problems.png

-Tero

-- 
Tero Matinlassi
Postipalvelimen ylläpito
Mail server administration