We have at least four diffrent applications in kdepim which send mails in one way or another (KMail, KNode, KOrganizer, KAlarm), so let's try to unify this a bit by sharing code and settings :)

So far we have:
- shared settings (synchronized via D-Bus), including password caching and async wallet handling (which are currently missing in KMail)
- config widgets
- basic migration of KDE3 kmail transport settings (hard to test given that KWallet stores data rather non-persistent here...)
- D-Bus interface
- a lot less handwritten code than currently in KMail thanks to KConfigXt and Qt Designer

Still todo:
- complete config migration
- mail sending job class
- port applications