Bug 343333

This is a common occurence currently:

1. Copy something to the clipboard.
2. plasmashell crashes and comes back.
3. Pasting now will paste very old data from the clipboard history.

This is unexpected behavior, because from the user's POV, the clipboard is global and not a function of the Plasma Desktop chrome. The clipboard mediates between applications, and since those stay running and visible, there's no reasonable connection to make between plasmashell flickering out of existence and back and clipboard data being replaced. I would not expect users to be understanding or caring about the implementation details involved.

It's also a data loss problem: If the previous clipboard contents were the only copy of the data, it's now gone.

There seem to be two ways to address this, possibly complimentary:

- Move the clipboard history back out of the plasmashell process as it was done in KDE 4. It really has no place being there (see above) and process separation for these distinct features would be a much more resilient design.

- Make Klipper serialize the history to persistent storage immediately instead of just at plasmashell exit.

Reproducible: Always