Support micros()

[Kaspi314]

It seems like delayMicrosecond would go hand in hand with supporting the micros() function. (like millis())

I'm not sure how to do this but I'll try to look into the datasheet about timers.

[nerdralph]

While microsecond delays are often needed for implementing protocols, the need for a microsecond-accurate timer is quite rare. Therefore this would be a low priority.

[Kaspi314]

Nothing comes to mind beyond laser range finding or something fast with a PID loop. I don't guess that the attiny is a great platform for it though and stm32 is more the norm for that. I guess milliseconds work well for most things especially with accuracy of 0.01 - 0.1ms.