Commit Briefs
cache listener flags in struct client
this saves us from the small chance that a client accepted before reconf uses the flags from a listener post reconf.
fix restart in listener
drop connections in the handshake phase: the listener from where they've been accepted is now being replaced and its id is no more meaningful. Clients for which we have already sent an auth request are kept.
use serial ids and drop usage of arc4random
it's not so useful here and not (directly) used anywhere else.
listener: correctly swap config after reload
and don't forget to free the current config!
fix the restart of the main process
delete useless functions such as merge_config and config_clear while here.