Referrer check breaks with UTF-8 URLs

[Studio384]

Let's assume a forum's base URL is configured with, say, Hebrew characters.

When accessing that forum with a browser, the request URL will be converted to contain Punycode. When comparing those two in confirm_referrer(), we will obviously not be successful.

What we could do is convert the base URL to Punycode in that function. That might be a little difficult, though, as we cannot use the idn_to_ascii() function in PHP before 5.3.0. Suggestions?

http://fluxbb.org/development/core/tickets/821/