Fixes needed

[xvart]

remove line 658 causes val_len to = -1

fix "Connection" handler to not barf on "keep-alive"

`
else if (key_len == 10 && !memcmp(data, "Connection", 10)) {
/**
* Fix for connection keep-alive
*/
if (memcmp(val, "keep-alive", strlen("keep-alive"))) {
if (memcmp(val, "Upgrade", 7)) break;
connection_checked = true;
}
}

`

Connection string used

GET / HTTP/1.1
Host: localhost:1234
User-Agent: Mozilla/5.0 (Unix; U; Linux 6.3.5-200.fc38.x86_64) http/2.9.5 Tcl/8.6.12
Connection: keep-alive
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: cZ7A+m2Pl1zuGlE1AcmnDA==
Sec-WebSocket-Version: 13
Sec-WebSocket-Protocol:
Accept: /
Accept-Encoding: gzip,deflate,compress

[MengRao]

Relaxed some http header validations, please check the latest commit.