Simplified stepper inactive time

if (millimeters_of_travel == 0.0) => if (millimeters_of_travel < 0.001)
(thanks mooselake)

One for common settings.
One for advanced settings.

Default off.

Needs some work to remove the blocking in read max6675.

Added late z enable. (blddk request)
Only calculate look ahead if >2 moves in buffer.
Removed some FORCE_INLINE to save memory.

Signed-off-by: Erik van der Zalm <erik@vdzalm.eu>

 arduino-0023/hardware/arduino/cores/arduino/wiring.h
this is necessary if the avr libraries are recent, but arduino is old. Alternative: newer arduino

advance and ultipanel not any more in default config

This reverts commit 651cde8b98.

Soft PWM. (Sanguinololu can also have PID temperature control)
Interrupt save WRITE for addresses > 0x0FF