pathfinding flags - unitst::status2::add_path_flags

[ab9rf]

this is being put here mainly to memorialize research notes

unitst::status2::add_path_flags is a bitmap the type of which is used as pathfinding flags

quietust reports that in 40d, these are (low bit to high bit): Desperate, Reckless, BuildingDestroyer1, BuildingDestroyer2, StuckInBuilding, AllowUnrevealed, Doors, UnkDoor7, CanLearn, Unk9, JumpCliff, Air, ShallowWater, DeepWater, UnderWater, ShallowMagma, DeepMagma, UnderMagma, InWater, InMagma, WalkLand, ImmobileLand, ZeroWalkTag, Unk23. there are likely additional flags in current for ghosts in the current version