[Monotone-devel] merging branch to allow 'automate stdio' over the network

[Timothy Brownawell]

I think branch net.venge.monotone.tbrownaw.serve_automate.single_port
is ready for merging. Instead of putting raw 'automate stdio' on the
network, this encapsulates it as netcmds and keeps the same initial
negotiation/authentication sequence (and the same 'bye' sequence) as
netsync.

This splits netsync.cc into multiple files, and splits the negotiation
and teardown out of the 'session' class. Then it adds 'automate_cmd'
as an alternative to 'anonymous_cmd'/'auth_cmd' so that network
clients can request either an automate connection or a netsync
connection.

This also adds an "automate remote_stdio <address>" command to make
use of these changes, and on the server side a
   get_remote_automate_permitted(identity, command, options)
hook which is checked for each automate command received and defaults
to "deny everything".