increased limit buffer size

Atm_AccelStepper.h

@@ -82,7 +82,7 @@ class Atm_AccelStepper: public Machine {
   bool limitHigh_State_raw;
   bool limitLow_State_prev;
   bool limitHigh_State_prev;
-  const static int limit_buf_size = 16 ;
+  const static int limit_buf_size = 20 ;
   bool limitLow_state_buf [limit_buf_size] ;
   int limitLow_state_total = 0 ;
   int limitLow_buf_head ;