fixed a strange bug that may or may not exist. sorry for so many updates

Increased size of EmpireStartZone so that all 6 cars can spawn in multiplayer.

Added yet more invisible walls to prevent yet more unintended skips. With the way the level is designed, there are almost certainly still skips if you try hard enough, but (hopefully) they all take at least 1:10 and a lot of effort, which I am okay with because the one actual intended skip also gives you about 1:10 time with a lot less effort.

Added invisible walls to remove one unintended skip, lowered a building that occasionally interfered in the flying section. There's still one skip that can get ~ 1:00 times, that one is (mostly) intended.