kdiff3: update to 1.8.5

Version 1.8.5 - 2021-01-10
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BUG:417189 Fix url handling for drag and drop.
BUG:426823 Fix regression in handing paste from clipboard to blank diff window.
*Fix link detection via KIO
*Drop custom event filter in OpenDialog. We now use FileNameLineEdit instead as in the main window.
*Fix url/path handling bugs for remote files
*Don't ignore stat errors unless it tells us the file was not found.

Version 1.8.4 - 2020-08-25
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*Fix typos in man page
*Fix compare over network with KIO
*Restore contextmenu for Windows Explorer

(gutteridge)