Add option to disable smooth scrolling
Even though the animated smooth scrolling transitions are now affected by the global animation speed setting in Plasma, this is not totally satisfactory for the full pool of people who hate smooth scrolling, as it does not address the cases of people using Okular outside of Plasma or people who generally want animations but just not in Okular's scrolling implementation.
Accordingly, there is now a GUI option to disable smooth scrolling in Okular's settings window.
BUG: 420755 FIXED-IN: 20.12