crow as ii follower commands

[trentgill]

add crow commands for reset & some asllib actions.
add s16ms type to descriptor system for using s16 to represent milliseconds (like teletype ms).

UNTESTED

The API for using crow as a follower has been changed:

ii.self.call = function(args)
  -- 'args' is a table
  -- use `#args` if you want to switch on the count of args (like the old call1, call2)
end

ii.self.query = function(args)
  -- 'args' is a table. use `#args` if you want to switch on arg count.
  return 0 -- here is where you return the value to the leader
end

All other commands & queries are handled directly by the crowlib. They typically should not be redefined by the user, though they can be if so desired. eg. ii.crow.reset() will trigger crow.reset() on the follower, but you could redefine this behaviour with ii.self.reset = function() <do something else here> end.

Will fix #258