Adding a few methods in motor.cpp to have the distinction between move and moveTo from the Accelstepper librairie. In fact I created same methods using moveTo but using move and I change comments t explin how it works.

I think it would be useful to see later if we are using all these methods
or if some of them can be deleted.

Add a limit switch status indication and using syringe_pump_off istaed of syringige_filled.move so the visual change a the same time

The problem was that i diddn't get the usefulness af the former attribute
retain_accel, which is useful for the use of the limit switch, I change
back the name and rename move_to_mm to move_to_mm_limit_switch and
move_mm to move_to_mm

Split motor.h into motor.h an motor.cpp, dding a few fuction (some setters missing and conversion) and adding comments.