Changes since previous release:
- fix binding TCP and UDP sockets to the same port, when specifying port 0
- fix announce_to_all_trackers and announce_to_all_tiers behavior
- fix suggest_read_cache setting
- back-off tracker hostname looksups resulting in NXDOMAIN
- lower SOCKS5 UDP keepalive timeout
- fix external IP voting for multi-homed DHT nodes
- deprecate broadcast_lsd setting. Just use multicast
- deprecate upnp_ignore_nonrouters setting
- don't attempt sending event=stopped if event=start never succeeded
- make sure &key= stays consistent between different source IPs (as mandated by BEP7)
- fix binding sockets to outgoing interface
- add new socks5_alert to trouble shoot SOCKS5 proxies