Add ron_u->liv

This prevents us from double-killing connections in races, e.g. the
one between _raft_rest_name and _raft_connect_cb.
update -> note, and call it
Rejigger connection killing
Clean up connections

The code seems much less racy now.
Comments
Unsigned format specifiers
Merge branch 'fucking-raft'
Remove trailing capnproto stuff
Fix long line
Longer heartbeat log interval
Log killed connections
Rejigger boot sequence

The calls to u2_raft_work were effectless since the log hasn't been
initialized by that point.
Clean up Raft options and init

I opted to keep u2_opts to just numbers, strings, and beans for now and
parse them to peer names in the Raft init code.
Log on bump to candidate
Add ++zing.
Merge branch 'master' of github.com:urbit/urbit
Redefined pfix, sfix in terms of comb, cleaned some variable names.
Pill with zing.
Merge branch 'master' of github.com:urbit/urbit
Fix a segfault on startup :(