when the initial data is larger than one MTU,
e.g. HTTP GETs with large URLs, CGI params or cookies,
or large HTTP POSTS:
- Don't reject additional packets received without a
send stream ID (i.e. sent before the SYN ACK was received)
- Put unknown non-SYN packets on the SYN queue also
so they won't be rejected
- Reduce flusher delay to 250ms (was 500)
- Flush unless window is full (was window is non-empty)