Might be used when tracker is behind reverse proxy and one of provided
addresses in `real_ip_header` is private/local address.
Additional changes:
* check if provided address is not multicast/broadcast
* configure `http.Server.ReadHeaderTimeout` with `http.ReadTimeout` to mitigate Slowloris
* update dependencies
* minor docs fixes
* add multiple addresses in request structures and frontend parsers
* move per-ip peer fetch/store from storage to internal hooks
* fetch/store both v1 and v2 info hashes
* remove peer argument from scrape swarm storage call
* replace Peer field with netip.Addr in ScrapeRequest
* add man for keydb storage
* update readme
* merge 9d04e4c from https://github.com/jzelinskie/chihaya
* sanitize ip address on Scrape requests
* remove NewConnectionID and ValidConnectionID functions from production code
* delete info hash count key from redis (replaced with SCARD on infohash set)
* add GC test
* add peer.Addr() functio to always return unwrapped address if 4to6 appear
