test neomatrix pixel level brightness setting and colours
to run this test download the 3 adafruit libraries from pwr33 as well which all have an extra parameter to drawpixel to allow pixel level brightness setting.
bright < 0 : use default panel brightness (defaults to -1 so parameter does not need to be used or passed)
bright = 0 : use unscaled rgb values
bright > 0 : scale this pixels brightness by bright value 1 = dimmest 255 = brightest