omg wow such pass

- removed ctxcloser
- removed multiconn
- focused on netio

This commit changes the connections to use io.ReadWriters
instead of channels (+ async workers). This is a pretty
big change -- away from csp -- in the name of performance
(and predictable flow control).

It also uses the brand new secio, which is spipe's successor.

fix: routing mock accuracy

License: MIT
Signed-off-by: Brian Tiger Chow <brian@perfmode.com>