This is a very early version of atmsigd that supports multiple signaling
entities in the same process. Everything's still a bit buggy and ugly.

To play with it, ...

1) Generate ATM interfaces 1 and 2:
  # atmtcp -b -i 1 -l
  # atmtcp -b -i 2 -c localhost
2) Create the following configuration file (name "config"):
  entity 1.0.5 { mode user route +1 }
  entity 2.0.5 { mode network default }
3) Launch atmsigd:
  # ./atmsigd.new -c config
4) Add local addresses:
  # atmaddr -a 1 +1
  # atmaddr -a 2 +2
5) Test it:
  % ttcp_atm -r -a
  % ttcp_atm -t -a +1

Known bugs:
 - wildcard bind removes wildcard
 - selection of local address isn't consistent with signaling interface
   selection
 - everything else that's marked with @@@
