added prompting

cubesatsim/cubesatsim.ino

@@ -4467,6 +4467,9 @@ void serial_input() {
 void prompt_for_input() {	
  float float_result;
 
+ if (!prompting) {	
+  prompting = true;	 
+	
   while (Serial.available() > 0)  // clear any characters in serial input buffer
     Serial.read();	  
 	
@@ -4839,6 +4842,8 @@ void prompt_for_input() {
 		  
   }
   prompt = false;
+  prompting = false;
+ }
 }
 
 void get_serial_string() {