Sending Pending Messages

In situations of communication failure with the SiTef server, the
CliSiTef will automatically send any remaining data (e.g.
example, commit, uncommit and undo data) only
in the next POS transaction.

However, it may take some time for the next transaction to start
at the station.

At times when the POS is in the rest or "idle" state, the
Automation can use the following routine to force the library to
download confirmation, unconfirmation and undo messages
to the SiTef server.

int DescarregaMensagens (void)

Upon return, the routine returns 0 if it managed to download all
messages and non-zero if an error occurs making it impossible to
sending them.