This is useful when using multiple interfaces and bridge.py is employed
as an application gateway between multiple un-connected networks (like
VPNs to the real world).
Previously, an unauthenticated network used a different class that
subclassed IPSC and overrode the the three functions that affect
authentication. Now, during class instantiation ( with __init__ ), the
set of functions are “aliased” depending on whether or not the IPSC’s
auth flag is set in dmrlink.cfg
Shebangs added to all files expected to be executed, command line
argument for configuration file added (otherwise, it looks for
dmrlink.cfg in the same directory as dmrlink.py) - this divorces it
from the last ties to a shell environment… or at least I think.
