Make DHCP non-blocking

[gigaj0ule]

I made DHCP requests non-blocking in a way that doesn't break the examples.

And I also renamed the SPI so that it would be easy for people to use non-default SPI

Is this useful?

I can make a P.R. if we want to merge these features.

[Olejan]

Yes, it is useful. Can you explain how to make non-blocking DHCP?

[TimoSEL]

Pls can you explain or share your non-blocking DHCP files?