Support different linebreaks in URLs

\n, \r, and \r\n are all OK in URLs when prefixed by a \. Currently only \n is supported due to some missing brackets.

I'm not sure whether the intention for these escapes is to maintain the escaped form or unescape it - it's inconsistent in that \n is stripped but the others aren't, but I'm reluctant to make it not strip the \n without knowing why it's doing it in the first place. So I just left things as is.