Bugfix: Attachments were not cleaned up on finish() call of mail class (next recipient gets all attachments, too)
Update: some import tests for plesk

Fixed/Implemented: replaced intval() by $app->functions->intval() in all interface functions due to big number problem in intval()

FS#2288 - Importer for data from Plesk control panel (first INCOMPLETE version, see bugtracker for status)