Pathfinding workarounds

[animats]

I've been able to work around many of the problems in pathfinding. I now have somewhat smoother motion and better behavior under sim overload. I've commented on this before. New notes:

• Pathfinding has two modes - really slow but more accurate (option CHARACTER_ACCOUNT_FOR_SKIPPED_FRAME  set to FALSE) and faster but less accurate (TRUE). If you run with this set to FALSE, the spinning and running into obstacle problems are less. But it's really slow if the sim has a shortage of script time. Pathfinding has even lower priority that scripts. A sim that's running 80% of scripts may be running only 30% of pathfinding cycles. In FALSE mode, the character will visibly slow down in proportion to the number of pathfinding frames executed, a number you can see in the statistics bar.
  
  I've been running in "fast" mode until the character bumps into something and records a collision. (Collisions with walkable objects have to be ignored; that's ground contact.) Then the character shifts to "slow" mode until 5 seconds without a collision. This workaround gets characters through tight spots without slowing them down in open space. Not perfect, but better than running in either mode full time.