* refactor: move tr_tracker_http_announce() helper funcs into their own namespace
* refactor: move tr_globalIPv6() helper funcs into their own namespace
* refactor: move tr_address_is_valid_for_peers() helper funcs into their own namespace
* refactor: make tr_address_compare() a private method
* refactor: rename tr_address::isIPv4() to is_ipv4()
* refactor: use snake_case for tr_address methods
* refactor: make tr_address_is_valid_for_peers() a member function
* refactor: make tr_peer_socket.type private
* refactor: reimplement tr_peerIo::address() as a wrapper around tr_peer_socket::address()
* refactor: remove tr_address, tr_port from tr_peerIo
* refactor: replace tr_netClosePeerSocket() with tr_peer_socket::close()
* refactor: remove tr_address_compare()
* refactor: remove tr_address_to_string()
* refactor: remove NUM_TR_AF_INET_TYPES
* refactor: replace tr_sessionGetPublicAddress with tr_session::getPublicAddress()
* refactor: tr_peerIo() takes tr_address by value
* refactor: replace tr_sessionIsAddressBlocked with tr_session::isAddressBlocked()
* refactor: tr_peerMgrAddIncoming now takes tr_address by value
* refactor: replace tr_address_is_valid_for_peers() with tr_address.isValidForPeers()
* refactor: tr_netOpenPeerSocket takes tr_address by value
* refactor: remove tr_generateAllowedSet()
* refactor: setup_sockaddr takes a tr_address by value
* refactor: tr_netBindTCP() takes a tr_address by value
* refactor: tr_dhtAddNode() takes a tr_address by value
* refactor: remove tr_address_from_string()
* refactor: rename tr_address.isValidForPeers() to .isValidPeerAddress()
* refactor: replace tr_address_from_sockaddr_storage() with tr_address::fromSockaddrStorage()
* refactor: minor cleanup to tr_address::readable()
* fix: ESPIPE "illegal seek" error while seeding
The root cause is createSocket returning `{}` instead of `TR_BAD_SOCKET`
when we have too many peers in use. This defaulted to fd 0, which wound
up closing stdin.
Commit also includes some const-correctness changes made while tracking
the problem down.
Charles Kerr