Since the class "MainMenu" was used within a static variable the
initialization of the object (constructor call) was done before Arduino
library startup. It always caused a crash when using AVRStudio with
JTAG debugger (caused from calling the LCD initialization / the lot of
I/O work / the stack used during this calls). By moving the LCD_INIT
out of the constructor and using an explicit call inside of Arduino
setup() implementation immediately fixed all problems and the JTAG
debugger runs fine.

"i" runs from 0 to 4 but "add_homeing" array size is 3 only. On the
other hand the calculated value gets overwritten by either one of the
if choice.

Changed SLOWDOWN. IF this does not work ok OLD_SLOWDOWN is the old algo.

Fixed small bug in arcs
M105 prints now actual_temp/target_temp

Moved the PID_dT in the Ki and Kd calculation from the configuration.h to temperature.cpp

M303 Starts autotune. Wait till the Kp Ki and Kd constants are printed.
Put these values in Configuration.h

Split ramps1.3 in Sprinter like config and multiextruder config.

Added M221 extuder multiply factor.

Updated the Xsteps ... settings via the LCD menu

Signed-off-by: Blair Thompson <mail@justblair.co.uk>

Simplified stepper inactive time

Simplified stepper inactive time

One for common settings.
One for advanced settings.

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>