Escaping for user agent and referer

[Dobatymo]

If the user agent or referer include double quotes ("), the log entries become unparsable because the quotes are not escaped and will look like
127.0.0.1 - - [16/Mar/2017:15:39:18 +0000] "GET / HTTP/1.1" 200 233 "ref" "erer" "user"agent"
Some simple backslash escaping (" and \) should be fine

The same issue might apply for requests, but i didn't check.