Small fixes, pathfinder renamed
- the default flag for if a zone has no flags is now -1 instead of 0. this prevents the pathfinder from moving through it
- remove PathFinder interface and rename SmartPathFinder to PathFinder
- set default distance value to just 999 to avoid overflow in bitpacking
- set default destination width and height to 1, as 0 is invalid. all elements are at least 1 tile in size