refactorings to support the remote_wal_listener

- The remoteWorker's local databsae connections is now stored
in the SlonNode structure and guarded by a mutex so the
remote_wal_listener thread can use it

-move the logic for selecting the current log table to its
own function so it can be reused
include the origin_id in the output by lookup up sl_set
basic support for moving data update rows from the walsender stream
to the worker database connection
init the string before using it
adding more logic for processing the output COPY stream from the wal_sender

This is still a work-in-progress
remove nosy log data
don't try to connect a provider to a walshipping provider remoteWALListener already does this
misc bug fixes still WIP
use our own FSM like parsing, strtok_r doesn't work well for this
sl_set should also be time-travelled
fix the processing of the slony cluster name via the options on
START LOGICAL REPLICATION