The maximum number of incoming streams doesn't need to be negotiated. It
is a value that is only announced by the peer, and has to be respected.
Furthermore, Chrome doesn't seem to care about the MSPC value anymore
(since MIDS was introduced), so there's no need to send this in the
handshake any more.
The idle timeout doesn't need to be negotiated, simply announcing it to
the peer is sufficient. We now close the session if there's no incoming
network activity for the duration of the local idle timeout, and we
send a PING frame after half the remote idle timeout (if keep alives are
enabled).
