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>

BenchmarkMixedAddCat1MBXX              2         517168259 ns/op 2.03 MB/s
BenchmarkMixedAddCat2MBXX              2         526999378 ns/op 3.98 MB/s
BenchmarkMixedAddCat4MBXX              2         543184846 ns/op 7.72 MB/s
BenchmarkMixedAddCat8MBXX              2         590800431 ns/op 14.20 MB/s
BenchmarkMixedAddCat16MBX              2         688463619 ns/op 24.37 MB/s
BenchmarkMixedAddCat32MBX              2         881731910 ns/op 38.06 MB/s
BenchmarkMixedAddCat64MBX              1        1254493054 ns/op 53.49 MB/s
BenchmarkMixedAddCat128MB              1        1941335608 ns/op 69.14 MB/s
BenchmarkMixedAddCat256MB              1        4748005512 ns/op 56.54 MB/s

@whyrusleeping

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