Add c-capnproto
Add _main_readw
Add raft listener/peers
Fix comment
New-style raft options
Skeleton for raft
Move srand call, seed from pid
Add raft.capnp
Make u2_reck_plan push to roe
WIP Make _lo_work rafty

Carts are now batches of events waiting to be or just recently
persisted. _lo_work calls u2_reck_kick on the last batch of events,
removes every batch that's been through Raft, and then prepares the next
batch.

TODO make _lo_punk et al stick things on roe

TODO move disk persistence to raft.c

TODO raft_push: lo_open / mark / lo_shut
WIP rafty loop.c

_lo_save() sticks events on roe for processing in later calls to
_lo_work().
WIP raft single instance

Shove all our disk stuff crudely into raft.c.
Trivial fixups
WIP Move lug_u to u2_raft
More loop -> raft, add u2_raft_boot
New event loop working, super rough cut
Write term and log type, in preparation for raft
Splinter disk persistence and reck stuff back out
WIP cleanup and fixes
Fix event playback