Added optional feature to stop printing when an endstop is hit. Made the Z display on the LCD in 3.2 format instead of 3.1. Added LCD message when and endstop is hit.

Marlin/stepper.h

@@ -37,6 +37,9 @@
   #define REV_E_DIR() WRITE(E0_DIR_PIN, INVERT_E0_DIR)
 #endif
 
+#ifdef ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED
+extern bool abort_on_endstop_hit;
+#endif
 
 // Initialize and start the stepper motor subsystem
 void st_init();