Add clipboard history dialog
This adds a clipboard history dialog (essentially like Klipper, but adjusted for code/text editors).
Benefits in comparison to the kate paste menu:
- better for longer text/multiple lines
- syntax highlighting
- great keyboard usability
Why do I need this, I have Klipper? Yes, but it's nice to have that feature integrated into all text editors in KDE software that use KTextEditor. Also, people on different desktop environments/window managers or OSs might not have access to a global clipboard history.
Open Questions/Problems:
- Performance: the constant re-highlighting is a big problem and it is too slow for a large file in general (e.g kateview.cpp) -> How is that done currently when opening files in Kate?
- I've copied over a few things from Kate. How do I handle this correctly? Obviously, we don't want code duplication. But can I “just” turn this into public API?
Note: This is my first time working with Qt model view classes.
P.S. I might not find much time to work on this during the next two weeks or so, but I wanted to hear what you think.