kdelibs point updates should suggest reboot

On kdelibs point or minor version updates, a reboot noticfication should be triggered, so that the user hopefully reboots.

When upgrading kdelibs it is also indicating that all of the KDE SC is being upgraded, thus it is important the user at the very least logs out and back in again, to prevent runtime issues caused by a version mismatch of say a kded module and an application using that module. Also, without relogin not all fixes get applied.

Therfore upon upgrades kdelibs should trigger a reboot notification (or possibly one should introduce a new relogin notification type?).

This can be archived via maintainer scripts, by stripping the revision part of the versions (i.e. only get the source version) and then compare the old and new version using dpkg. There is however the problem that the maintainer scripts do not get called with both versions at the same time, so it is probably necessary to write the old version, via the old prerm script, to some file in /tmp, then read this file in the new postinst and depending on the comparision of old and new version either touch the reboot trigger file or not.