Since the datasheet cast some doubt on the strength of the "rosc_hw->randombit",
I use the SHA256 hash function to create a high quality random seed
from random values of uncertain entropy, as well as to generate a sequence
of random values from that seed using SHA256 as a cryptographically-secure
random number generator.
In practice, it produces over 100kB/s of random data which does not
have any gross problems according to _PractRand_.
Everyone loves to names similar things the same, then there're conflicts
between different libraries. The namespace prefix used is "CRYAL_", which
is weird, and that's good, as that minimizes chance of another conflict.