QUIC: ignore duplicate PATH_CHALLENGE frames. According to RFC 9000, an endpoint SHOULD NOT send multiple PATH_CHALLENGE frames in a single packet. The change adds a check to enforce this claim to optimize server behavior. Previously each PATH_CHALLENGE always resulted in a single response datagram being sent to client. The effect of this was however limited by QUIC flood protection. Also, PATH_CHALLENGE is explicitly disabled in Initial and Handshake levels, see RFC 9000, Table 3. However, technically it may be sent by client in 0-RTT over a new path without actual migration, even though the migration itself is prohibited during handshake. This allows client to coalesce multiple 0-RTT packets each carrying a PATH_CHALLENGE and end up with multiple PATH_CHALLENGEs per datagram. This again leads to suboptimal behavior, see above. Since the purpose of sending PATH_CHALLENGE frames in 0-RTT is unclear, these frames are now only allowed in 1-RTT. For 0-RTT they are silently ignored.

geo2nginx.pl 		by Andrei Nigmatulin

	The perl script to convert CSV geoip database ( free download
	at http://www.maxmind.com/app/geoip_country ) to format, suitable
	for use by the ngx_http_geo_module.


unicode2nginx		by Maxim Dounin

	The perl script to convert unicode mappings ( available
	at http://www.unicode.org/Public/MAPPINGS/ ) to the nginx
	configuration file format.
	Two generated full maps for windows-1251 and koi8-r.


vim			by Evan Miller

	Syntax highlighting of nginx configuration for vim, to be
	placed into ~/.vim/.