UBL's Grid Based Leveling code

Pretty much...  The code is in place.  Still more work to do.    But it
has a lot of hooks and variables in other code, so commit and merge
before I pick up a million 'Conflicts'.

Marlin/Marlin_main.cpp

@@ -1983,8 +1983,6 @@ static void clean_up_after_endstop_or_probe_move() {
     #endif
   #endif
 
-  #define DEPLOY_PROBE() set_probe_deployed(true)
-  #define STOW_PROBE() set_probe_deployed(false)
 
   #if ENABLED(BLTOUCH)
     void bltouch_command(int angle) {