Simplify and comment pathfinding.
Rework linedef type information and split sector moving parameters.

Linedef types are now stored in more detail in a configuration object.
This way we can now know whether a sector's floor or ceiling moves
independently, and connect paths through special sectors accordingly.
E1M3's little door overlooking the secret room was previously elegible
for pathing through because it's ceiling can move during gameplay.

Hexen map support is currently broken.