Check if input is a valid stop id

libdata.php

@@ -54,6 +54,17 @@ function isValidLine($line){
     return false;
 }
 
+function isValidStop($stp){
+    global $stops;
+    foreach ($stops as $stop){
+        if ($stop['id'] == $stp){
+            return true;
+        }
+    }
+    return false;
+}
+
+
 function getRouteInfo($id){
     global $routes;
     foreach ($routes as $route){