Fixes Issue 806
Make sure to close opened folders in finally blocks in
MessagingController.
Don't make another connection when deleting or copying a
message. (Nicely speeds up copy and delete, as well.)
Another connection is still created for creating a folder while
copying or deleting (a pretty rare event), and the IMAP IDLE
connections are not re-used for user initiated activity.
On each IMAP account, the expunge behavior can be set to expunge
messages in a folder as soon as a move or delete is performed on the
folder ("immediately"), each time the folder is polled, or only when
executed manually.
In the Message List, there is now an Expunge action in the option
menu.
In the Folder List, there is now an Expunge action in the context
menu (long-press on the folder).
For IMAP accounts, it is also possible to disable the copying of deleted messages to the
Trash folder, by setting the Trash folder to -NONE-.
Fixes Issue 536.
Separately, in WebDAV accounts, the user can now choose the
server-side equivalents of the special folders, just like for IMAP.
