probe: Add support for samples_tolerance

Add a check on the maximum Z distance between probe samples.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

config/example-extras.cfg

@@ -39,6 +39,18 @@
 #samples_result: average
 #   The calculation method when sampling more than once - either
 #   "median" or "average". The default is average.
+#samples_tolerance: 0.100
+#   The maximum Z distance (in mm) that a sample may differ from other
+#   samples. If this tolerance is exceeded then either an error is
+#   reported or the attempt is restarted (see
+#   samples_tolerance_retries). The default is 0.100mm.
+#samples_tolerance_retries: 0
+#   The number of times to retry if a sample is found that exceeds
+#   samples_tolerance. On a retry, all current samples are discarded
+#   and the probe attempt is restarted. If a valid set of samples are
+#   not obtained in the given number of retries then an error is
+#   reported. The default is zero which causes an error to be reported
+#   on the first sample that exceeds samples_tolerance.
 #activate_gcode:
 #   A list of G-Code commands to execute prior to each probe attempt.
 #   See docs/Command_Templates.md for G-Code format. This may be