Make the test "array is a list" a bit more robust

We are looking for an integer, excluding other numeric values (decimals, etc).

As a reminder: for array keys, PHP automatically casts strings representing integers to regular integers.

Author: vlakoff

system/Database/Query.php

@@ -281,7 +281,7 @@ protected function compileBinds()
 
         $binds = (array) $this->binds;
 
-        if (is_numeric(key(array_slice($binds, 0, 1)))) {
+        if (is_int(key(array_slice($binds, 0, 1)))) {
             $bindCount = count($binds);
             $ml        = strlen($this->bindMarker);