Replaced the Custom AI with the Jusk-produced version that adds new variants to the behavior of AI pilots.
- Added the new 'avoidance_of_mistakes' and 'avoidance_of_forced_mistakes' attributes to all drivers
- Added some track specific overrides - e.g. making Al Unser Jr slightly better at Long Beach
- Added some track specific overrides to switch drivers (e.g. replacing Eddie Cheever with Fredrik Ekblom at Laguna Seca).
My thanks to chrisi2174 and jusk for their generous contributions.
