Optimize struct unpacking

[tannewt]

x = struct.unpack('<h', data[0:2])[0]
y = struct.unpack('<h', data[2:4])[0]
z = struct.unpack('<h', data[4:6])[0]

Slicing data causes an extra allocation. Struct should be able to take the whole buffer and split out the values at once.

[mrmcwethy]

I have a fix to Adafruit_Circuitpython_LIS3DH issue #7 Optimize struct unpacking in my development env. Can someone assign it to me or allow me contributor rights?

[mrmcwethy]

This issue is fixed as of oct 4, 2017