Removed old helper file

src/inline_protocol_functions.php

@@ -1,15 +0,0 @@
-<?php
-namespace InfluxDB;
-
-function list_to_string(array $elements, $escape = false)
-{
-    array_walk($elements, function(&$value, $key) use ($escape) {
-        if ($escape && is_string($value)) {
-            $value = "\"{$value}\"";
-        }
-
-        $value = "{$key}={$value}";
-    });
-
-    return implode(",", $elements);
-}