Move new default folders to default position in folder listtree

Phenomenon

Currently when a default folder (incoming, drafts, etc.) is added because it doesn't exist yet it will be added at the bottom of the folder listtree. Better would be to add it at a sensible place with an internally defined order.

Background analysis

E.g. when adding the "Drafts" folder it should appear right after the "Incoming" folder. A sensible default folder order could be:

1) Incoming
2) Drafts
3) Outgoing
4) Sent
5) Trash
6) Spam

Implementation recommendation