Receiving an http request/response will now return errors like HttpHeaderTooBig, instead of the type being set to that.
Added fr::Socket::status_to_string for converting status values into English strings.
fr::HttpSocket has been removed.
fr::Sendable has been added. Classes can inherit this if they want to be sendable through sockets. Both fr::Http (which is inherited by fr::HttpRequest and fr::HttpResponse), and fr::Packet inherit this, to allow them to be sent through fr::Socket::send()/fr::Socket::receive().
Fixed broken fr::SocketSelector and fr::SocketReactor, as they no longer accepted fr::Listener's due to fr::Listener no longer inheriting fr::Socket.
Fixed Content-Length header being added to Http responses even if there's a pre-existing one.
Fixed header parsing sometimes adding a carriage return to the header value.
Removed useless copy/move constructors from HttpResponse, causing issues.
Build errors have been fixed, but there are build warnings remaining about unsafe conversions, because Visual C++'s network conversion functions have a differing return type to mine. To be fixed in the future.
