Default to 2-finger emulation when HW supports it
Default to 2-finger emulation when HW supports it

Ideally, emulating 2-fingers should just work on hardware
were it can be supported. This patch is to do that.

Currently, emulateTwoFingerMinW defaults to 7. Most kernel
drivers do not support reporting finger width and so can't get above
MinW of 7. Synaptics devices hardcode width value to 5 when
hardware doesn't support width and 7 is a good threshold to detect
2 fingers on hardware that does. bcm7954 are only other devices
that report width and they support reporting DOUBLETAP and wouldn't
need emulation anyways.

emulateTwoFingerMinZ defaulted to a really high value so never
let Synaptics devices to emulate 2-fingers by default.
Changed default to a low value (same as FingerHigh) when hardware
doesn't support DOUBLETAP and supports width so emulations
will now work by default in all the right cases.

I'm working to get kernel to stop reporting ABS_TOOL_WIDTH unless
hardware really supports it.  If that would have been behavior
in first place then we could also default to 2-finger scrolling as
well.  Since its not reliable, we should continue defaulting to
side scrolling.

Config GUI's will want to now allow switching between 2-finger and edge
scrolling when new property indicates width is supported.  GUI's should
also update the above MinZ and MinW's to values similar to our defaults.

Signed-off-by: Chris Bagwell <711c73f64afdce07b7e38039a96d2224209e9a6c@cnpbagwell.com>
Signed-off-by: Peter Hutterer <b9c50af7afa7642f6f854434cda9ffe54ece8b85@who-t.net>

nanderson94/xf86-input-synaptics,kelnos/xf86-input-synaptics,philipn/xserver-xorg-input-synaptics,ssaavedra/xf86-input-synaptics,joeshaw/xf86-input-synaptics,ssaavedra/xf86-input-synaptics,nanderson94/xf86-input-synaptics,RsrchBoy/xserver-xorg-input-synaptics,quadpixels/three-finger-dragging,gdestuynder/xf86-input-synaptics,mmonaco/xf86-input-synaptics,sencer/synaptics,sencer/synaptics,philipn/xserver-xorg-input-synaptics,felipejfc/xserver-xorg-input-synaptics,RsrchBoy/xserver-xorg-input-synaptics,mortehu/xf86-input-synaptics,Lyude/xf86-input-synaptics,gdestuynder/xf86-input-synaptics,joeshaw/xf86-input-synaptics,eyko/xf86-input-synaptics,corcoran/xserver-xorg-input-synaptics,quadpixels/three-finger-dragging,eyko/xf86-input-synaptics,felipejfc/xserver-xorg-input-synaptics,Lyude/xf86-input-synaptics,mortehu/xf86-input-synaptics,jiixyj/xf86-input-synaptics,corcoran/xserver-xorg-input-synaptics,kelnos/xf86-input-synaptics,mmonaco/xf86-input-synaptics,jiixyj/xf86-input-synaptics,philipn/xserver-xorg-input-synaptics,felipejfc/xserver-xorg-input-synaptics