Log levels
==========

From v1.12, Pbox allows you to selectively turn off different types of log
messages. There is a new system_dat entry, LOGLEVEL = n  where n is a number
from 0 to 255, and is used as a bitmask.

Messages are only logged if "loglevel" has the relevant bit set.
This is not a full list of all messages, just an idea of which
category different messages will fall into.

Bit     Usage
===     =====

 0      Basic call info. Things like "mail session", "waiting for call"

 1      Basic user positions. "main menu", "info menu", names of programs

 2      More detailed user positions. "replying to message", "downloading
        tagged files", "checking for new mail"

 3      Internal program progress. "showing logoff screen","searching for xxx"

 4      More detailed program progress "downloading xxx",
        "reading message nnnn"

 5      Warnings to user. "Download limit exceeded","Failed tag","Time limit
        expired". Anything causing a program to stop.

 6      Modem commands/responses

 7      Keypresses. Invalid menu choices. "RCV x","menu option x"
