Logitech DJ

WORKING:
- move the pointer (although at slower acceleration than non-raw)
- tap to click
- two fingers tap to trigger "middle click"
- three fingers tap to trigger "right click"
- two finger vertical/horizontal scrolling

Note: by default two finger horiz scrolling was disabled, to enable, use:
xinput --set-prop 'Logitech Unifying Device. Wireless PID:4101' 'Synaptics Two-Finger Scrolling' 1 1
(horizTwoFingerScroll is hard-coded FALSE in
src/synaptics.c:615#set_default_parameters, use xorg.conf or above xinput to
change this)

Not working (presumably not supported by xf86-input-synaptics, no xev events):
- back/forward gesture with three fingers
- other gestures with four fingers

(1)
When a device sends a non-DJ report (i.e. HID++) one can see the following log:
	hid-logitech-dj:logi_dj_raw_event (size=20) 11 02 0f 00 00 0b 00 00 00 00 00 00 05 00 00 00 00 00 00 00
	logi_dj_recv_forward_raw_report:warning, dropping report to device index:2
To fix, send the enumeration message at probe time.

(2)
Related to (1), if driver receives DJ report, it keeps sending enumeration
report until the device is known. Perhaps consider the 'connected' property
before sending a new enumeration report?

(3)
pressure is always reported as 0 for WTP?! (workaround applied, need to ask
Nestor about this, perhaps it's a firmware bug)

(4)
Related to (1)? When mouse is moved while not known by the driver (e.g. driver
reloaded while mouse was in radio range and connected), I see:
	logi_dj_recv_forward_raw_report:hid_input_report returned error:-19
	(19 is -ENODEV)
	hid-logitech-dj:logi_dj_raw_event (size=15) 20 01 02 00 00 00 f0 ff 00 00 4f 00 00 00 00
Same for touchpad, but then turning off/on does not help