Device should seed random generator

[pelikhan]

Random currently returns always 0.

[jamesadevine]

@pelikhan try https://github.com/lancaster-university/codal/tree/rng, random_value was not being set.

[jamesadevine]

(have no device to test it on, hence the separate branch)

[finneyj]

:-) just fixed it @jamesadevine

push coming up...

[jamesadevine]

I'll delete my patch then? 😉

[finneyj]

I'll let you decide which is best...

[finneyj]

Fixed on my tests...

@pelikhan There's now a static default "0xC0DA1" to protect against a seed never being set, and I've also added a line here that shows how to seed it with a non deterministic value for CircuitPlayground... You might want to do this in PXT too:

https://github.com/lancaster-university/codal-adafruit-cplay/blob/master/source/CircuitPlayground.cpp#L75

Can you please test and close if it works for you...