xwiishow: print accelerometer information

This extends the xwiishow tool to print accelerometer events if the
accelerometer has been enabled.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
xwiishow: print IR data

This allows to toggle the IR cam with the "i" key. If IR data is received,
all four trackable points are displayed in a new IR section.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>