Used to find paths in a FlxBaseTilemap. extend this class and override
getDistance to create you're own! For top-down maps, it may
be wiser to extend FlxDiagonalPathfinder, as it already has a lot of basic helpers.
To use, either call
myPathfinder.findPath(myMap, start, end) or
myMap.findPathCustom(myPathfinder, start, end)