Fix faux scrolling for line-based touchpads
Fix faux scrolling for line-based touchpads

Touchpads which use line-based instead of pixel-based updates send
partial scroll requests, so decimal numbers are important. The current
implementation only really used scroll amounts that are either 1 or -1.

This has been fixed and now the line-based touchpads should have very
smooth scrolling, but the pixel-based approach is still WIP and
completely untested.

jwilm/alacritty,jwilm/alacritty,jwilm/alacritty,jwilm/alacritty,alacritty/alacritty,alacritty/alacritty