(At least) openSUSE uses ~/.kde4 to store KDE4 settings.
This patch changes ~/.kde/ to ~/.kde{,4} in all abstractions.

The patch is mostly from Velery Valery, I only fixed a merge conflict 
and added the kmail{,2} part in private-files-strict.

References: https://bugzilla.novell.com/show_bug.cgi?id=741592

Acked-By: Steve Beattie <sbeattie@ubuntu.com> for both trunk and 2.7.