Don't poll for POLLOUT events in schedule_accept.

Hello, I found what I'd call an oversight in one of the startup routines. It
registers the listening filedescriptor to get both POLLOUT|POLLIN events,
the former does not really make sense here. This seems to be ignored by the
glibc/linux but when I try to run it inside cwrap's socket_wrapper I get
infinite loop where polipo tries to accept() on the socket and gets told
there isn't anything connecting.
Update URLs in manual.
Update DNS section in manual.
Update .gitignore.