add is idle condition on RGBL lib

lib/GRBL/src/GRBL.cpp

@@ -32,3 +32,13 @@ void GRBL::mouveForward(int mm){
     sprintf(s, "G1 X%d", mm);
     this->grbl->sendGcode(s);
 }
+
+bool GRBL::isIddle(){
+    bool sortie = false;
+
+    if(this->grbl->readStatus().indexOf("IDLE") != -1){
+        sortie = true;
+    }
+
+    return sortie;
+}