bug#57970: 29.0.50; Create new defgroup for pixel-scroll.el

[Po Lu]

Stefan Kangas <stefankangas@gmail.com> writes:

> I'm still not sure what is the relationship with pixel-scroll-mode.  Eli
> does, I think.  So it might be best to send any suggested changes to the
> bug tracker.

For what it's worth, the only advantage the old pixel-scroll-mode has
over p-s-p-m is that it functions with regular wheel mice by default.

pixel-scroll-precision-mode is also capable of supporting wheel mice,
but detecting them and enabling the requisite options is tricky and
subject to numerous edge cases, so those options remain off by default.