Allow annotated output

[Travis F. Collins]

Enhance device output to provide names of associated data. This is really helpful for IMUs and sensors.

example:

dev = adi.adis16440()
out = dev.rx()
{'anglvel_x': array([-31.,  23.,  31., ...,  38.,  22., -17.]),
 'anglvel_y': array([-31.,  23.,  31., ...,  38.,  22., -17.]),
 'anglvel_z': array([-31.,  23.,  31., ...,  38.,  22., -17.])}