[USABILITY] Change the default input driver from synaptics/evdev to libinput

[GabMus]

Synaptics/evdev have been deprecated as stated here: https://bugzilla.gnome.org/show_bug.cgi?id=764257#c12
Still Antergos installs both instead of the new standard input driver xf86-input-libinput.
This causes unexpected behavior, like GNOME mouse settings not showing the touchpad at all, and inverting the two fingers and three fingers taps (normally 2 fingers is right click, 3 fingers is mouse wheel click; with synaptics/evdev since GNOME 3.20 2 fingers gives a mouse wheel click and 3 fingers a right click).

Consider defaulting to libinput

[slacka]

One point to consider is that xf86-input-libinput is still missing many basic features that synaptics supports such as palm detection.

[lots0logs]

Indeed. That is why we're holding off on this for now.

[slacka]

I tried defaulting to libinput and my cursor started jumping around the screen as described here. We should definitely hold off for a bit.

EDIT: this and many issues fixed in xf86-input-libinput 0.23.0-1. When that goes into Extra, we should reconsider.