Z_PROBE_REPEATABILITY test

Z_PROBE_REPEATABILITY test for Auto Bed Leveling.
Implemented as M48 with extra user specified options.
Full support at
http://3dprintboard.com/showthread.php?2802-Auto_Bed_Leveling-Z-Probe-Repeatability-code
Fix Default Configuration so Auto Bed Leveling is off

This snapshot has the Auto Bed Leveling turned off because most Marlin
users do not have that feature.
Merge pull request #1031 from Roxy-3DPrintBoard/Z_PROBE_REPEATABILITY-with-correct-Defaults

Z probe repeatability with correct defaults