This device looks similar to a MT device on the kernel side, but it's not a
MT device and it's not quite a tablet either. It uses slots to track up to 4
totems off the same device and the only hint that it's not a MT device is that
it sends ABS_MT_TOOL_TYPE / MT_TOOL_DIAL.

udev thinks it's a touchscreen and a tablet but we currently init those
devices as touchscreen (because all wacom tablet touch devices are udev
tablets+tochscreens). So we need a quirk to hook onto this device.

And we use a completely separate dispatch implementation, because adding the
behavior to the tablet interface requires so many exceptions that it's easier
to just add a separate dispatch interface.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>