* Moves PriorityQueue data structure out of the AStar file, and into it's own file in /__DATSTRUCTURES
* Adds Stacks, a data structure, to /__DATASTRUCTURES
* Adds Linked Lists, a data structure, to /__DATASTRUCTURES
Fixes poly from smashing herself constantly against windows trying to reach unreacheable items.
Changed the way AStar selects the adjacent turfs from each turf, taking in count the capabilities of the object or mob who will move. For example, being able to pass over tables.
The new system will use the bitflag atmos_adjacent_turfs to reach for adjacent turfs and CanPass().
Fixes#436