Improved homing cycle. New settings: homing enable/rates, debounce and step idle lock time.

- Homing cycle will now cycle twice (spec more/less in config) to
improve repeatability and accuracy by decreasing overshoot.

- New Grbl settings added: Enable/disable homing cycles, homing seek
and feed rates, switch debounce delay, and stepper idle lock time.

- Please note that these settings may change upon the next push, since
there will be more added soon. Grbl *should* not re-write your old
settings, just re-write the new ones. So, make sure you keep these
written down somewhere in case they get lost from a code bug.

- Refactored settings migration to be a little smaller and managable
going forward.

config.h

@@ -84,15 +84,6 @@
 // This parameter must be one or greater, currently supporting up to a value of 6.
 #define N_COORDINATE_SYSTEM 1
 
-// This parameter sets the delay time before disabling the steppers after the final block of movement.
-// A short delay ensures the steppers come to a complete stop and the residual inertial force in the 
-// CNC axes don't cause the axes to drift off position. This is particularly important when manually 
-// entering g-code into grbl, i.e. locating part zero or simple manual machining. If the axes drift,
-// grbl has no way to know this has happened, since stepper motors are open-loop control. Depending
-// on the machine, this parameter may need to be larger or smaller than the default time.
-// NOTE: If the define commented, the stepper lock will be disabled upon compiling.
-#define STEPPER_IDLE_LOCK_TIME 25 // (milliseconds) - Integer > 0
-
 // The temporal resolution of the acceleration management subsystem. Higher number give smoother
 // acceleration but may impact performance.
 // NOTE: Increasing this parameter will help any resolution related issues, especially with machines 
@@ -102,7 +93,7 @@
 // round-off can be great enough to cause problems and/or it's too fast for the Arduino. The correct
 // value for this parameter is machine dependent, so it's advised to set this only as high as needed.
 // Approximate successful values can range from 30L to 100L or more.
-#define ACCELERATION_TICKS_PER_SECOND 50L
+#define ACCELERATION_TICKS_PER_SECOND 60L
 
 // Minimum planner junction speed. Sets the default minimum speed the planner plans for at the end
 // of the buffer and all stops. This should not be much greater than zero and should only be changed
@@ -129,6 +120,11 @@
 // time step. Also, keep in mind that the Arduino delay timer is not very accurate for long delays.
 #define DWELL_TIME_STEP 50 // Integer (1-255) (milliseconds)
 
+// Number of homing cycles performed after when the machine initially jogs to limit switches.
+// This help in preventing overshoot and should improve repeatability. This value should be one or 
+// greater.
+#define N_HOMING_CYCLE 2 // Integer (1-128)
+
 // ---------------------------------------------------------------------------------------
 // FOR ADVANCED USERS ONLY: 
 
@@ -174,7 +170,14 @@
   #define DECIMAL_MULTIPLIER 100
 #endif
 
-//  Limit step rate for homing
-#define LIMIT_DEBOUNCE 50  // Limit switch debounce delay (in ms)
+// This parameter sets the delay time before disabling the steppers after the final block of movement.
+// A short delay ensures the steppers come to a complete stop and the residual inertial force in the 
+// CNC axes don't cause the axes to drift off position. This is particularly important when manually 
+// entering g-code into grbl, i.e. locating part zero or simple manual machining. If the axes drift,
+// grbl has no way to know this has happened, since stepper motors are open-loop control. Depending
+// on the machine, this parameter may need to be larger or smaller than the default time.
+// NOTE: If the define commented, the stepper lock will be disabled upon compiling.
+// -> NOW INSTALLED IN SETTINGS #define STEPPER_IDLE_LOCK_TIME 25 // (milliseconds) - Integer > 0
+
 
 #endif