We work out which ant we are by looking to see what marks ants ahead of
us are laying down. As marks can propogate twice as fast in ant ID order,
and signals are propogating from the lead ant back through the colony, we
start by turning left twice.

The precise algorithm has a reasonable amount of complexity to cope with
the keeper structure (keeper.txt), but the gist of it is:

* Look ahead
* Look left
* Look right
* If left and right were both clear we are the lead ant. Set a marker.
  (the other keeper members will use this marker to work out who they
   are, and will communicate this to the other keepers with signals of
   their own)
* If left and ahead were clear then we are on the left front row.
  Set marker 2, then marker 0.
* If right and ahead were clear then we are on the right front row.
  Set marker 1, then marker 0.

Each ant who doesn't know where he is then alternates looking for marker 2
and marker 1 ahead, 6 times each. In the first three times looking for
marker n it sets n then 0. In the latter 3 times it only sets n.
See markers.txt for more details on what this is doing (other than ant
identification).

Finally, if an ant still doesn't know who he is, he is either along the
column in the middle or at the back. He sets marker 0.

Dependent on when the ant worked out what sort of ant it is it then goes
off in a direction so that the net effect is that the ants spread out in
sensible directions giving a reasonably even split.