Go back to a 125 kHz sysclock for the 4 MHz crystal for now. Running at
32 kHz is presently incompatible with random().
Add freestanding and full warning compiler flags
.o, .hex and .elf don’t belong in the repo.
1. Use a faster PRNG. The one in libc is too slow for a 32 kHz system
clock.
2. Now that THAT’S sorted out, go back to using a ~32 kHz prescale for
4 MHz crystals.