Demonstration of Output Compare interrupt

A minimalistic program to show how we can flash a LED
using output compare.
CTC mode did not actually matter after all

My timer compare match program did not originally work because
I filled OCR0B with 128 instead of OCR0A, which is the only register which
may be used with CTC. Thus since OCR0A then would be 0, we only got the interrupt
triggered once. Exactly why did is I am not sure.

We could set both OCR0B and OCR0A. OCR0A would decide frequency while OCR0B would decide
how much the phase would be shifted.
Using ADC to adjust LED blinking frequency