* master:
  go/neo/neonet += Join
  go/neo/xtls: New package to build TLS configs for peer-to-peer internetworking
  go/zodb/zeo: Close networkers

The utility to create Networker suitable for interoperating with nodes
in a NEO cluster, be it TCP, TLS/TCP, TLS/lonet, etc. See added comments
for details.

See ConfigForP2P comment for details.

xnet.Networker added Close recently and is now required to be explicitly
closed by the user:

go123@01a77bb9

This fixes

    === RUN   TestLoad/go/!ssl
    I: runneo.py: /tmp/neo907773749/1 !ssl: started master(s): 127.0.0.1:25540
    I: runneo.py: /tmp/neo907773749/1 !ssl: terminated
    I: runneo.py: /tmp/neo907773749/1 !ssl: started master(s): 127.0.0.1:21414
    I: runneo.py: /tmp/neo907773749/1 !ssl: terminated
        xtesting.go:297: load 0285cbacc06d3a4c:0000000000000007: returned err unexpected:
            have: neo://[::]:42091/1: load 0285cbacc06d3a4c:0000000000000007: NOT_READY: data corrupt: len(hash) = 0
            want: neo://[::]:42091/1: load 0285cbacc06d3a4c:0000000000000007: 0000000000000007: object was deleted @0285cbacc06d3a4c
        xtesting.go:297: load 0285cbad858bf2e6:0000000000000006: returned err unexpected:
            have: neo://[::]:42091/1: load 0285cbad858bf2e6:0000000000000006: NOT_READY: data corrupt: len(hash) = 0
            want: neo://[::]:42091/1: load 0285cbad858bf2e6:0000000000000006: 0000000000000006: object was deleted @0285cbad858bf2e6
        xtesting.go:318: load 7fffffffffffffff:0000000000000006: returned err unexpected:
            have: neo://[::]:42091/1: load 7fffffffffffffff:0000000000000006: NOT_READY: data corrupt: len(hash) = 0
            want: neo://[::]:42091/1: load 7fffffffffffffff:0000000000000006: 0000000000000006: object was deleted @0285cbad858bf2e6
        xtesting.go:318: load 7fffffffffffffff:0000000000000007: returned err unexpected:
            have: neo://[::]:42091/1: load 7fffffffffffffff:0000000000000007: NOT_READY: data corrupt: len(hash) = 0
            want: neo://[::]:42091/1: load 7fffffffffffffff:0000000000000007: 0000000000000007: object was deleted @0285cbacc06d3a4c

See also bc2cddfc (X go/neo: Switch to NEO-kind SHA1)