Add the socalled "Babystepping" feature.

It is a realtime control over the head position via the LCD menu system that works _while_ printing.
Using it, one can e.g. tune the z-position in realtime, while printing the first layer.
Also, lost steps can be manually added/removed, but thats not the prime feature.
Stuff is placed into the Tune->Babystep *

It is not possible to have realtime control via gcode sending due to the buffering, so I did not include a gcode yet. However, it could be added, but it movements will not be realtime then.

Historically, a very similar thing was implemented for the "Kaamermaker" project, while Joris was babysitting his offspring, hence the name.

say goodby to fuddling around with the z-axis.

Marlin/temperature.h

@@ -53,6 +53,11 @@ extern float current_temperature_bed;
   extern float bedKp,bedKi,bedKd;
 #endif
   
+  
+#ifdef BABYSTEPPING
+  extern volatile int babystepsTodo[3];
+#endif
+  
 //high level conversion routines, for use outside of temperature.cpp
 //inline so that there is no performance decrease.
 //deg=degreeCelsius