Bot falls off ledges

[ioan-chera]

The bot has bad velocity control, and it tends to easily fall off ledges when doing L turns next to ledges. It happens in E1M3, as it falls into the outdoors slime pit when trying to pick some ammo and then go along the ledge.

[ioan-chera]

It can happen because the bot chooses the closest point of the next subsector boundary. It can be right at the end of it, which might intersect with an unrelated boundary that can fall into a pit. No matter how careful the bot would move there, chances are overwhelming that it will slip off.

[sneakernets]

I noticed this yesterday when testing through episode 1. rarely does it not fall.

[ioan-chera]

A couple of problems have been fixed:

1. Don't go for the very endings of the crossing lines. This should prevent the pitfall pictured above.
2. Based on current velocity, calculate the stopping distance. If at this distance there's a pit, make the bot slow down just in time.

There are still problems in some maps, e.g. Fava Beans E1M5 at the death pit near the exit.