This parameter was added as a workaround for our fast trackpad
scrolling. Since that was fixed before 1.0 shipped, in #4554, it has
been largely vestigial. There is no reason for us to keep it around any
longer.
It was also the only "logic" in TerminalSettings, which is otherwise a
library that only transits data between two other libraries.
I have not removed it from the schema, as I do not want to mark folks'
settings files invalid to a strict schema parser.
While I was in the area, I added support for "scroll one screen at a
time" (which is represented by the API returning WHEEL_PAGESCROLL),
fixing #5610. We were also storing it in an int (whoops) instead of a
uint.
Fixes#5610
06b50b47ca