A\* Pathfinding
===============

There are 3 main values usedd in reference to A\*:

    f = how promisiing a new location is
    g = distance from origin
    h = estimate distance to goal
    f = g + h

For a grid space our `h` is calculated by two straight shots to the goal
from the current location(ignore barriers). The grid space `g` value is
basiccally the number of steps we've taken from the origin. We maintain
a list of potential nodes only, so if one of the seeking nodes gets us
stuck we can freely remove that, because it succs.

Time & Space Commplexities
==========================

Best-First Search
-----------------

Time: O(VlogV + E)

Dijkstra's
----------

O(V\^2 + E)

A\*
---

Worst case is the same as Dijkstra's time

O(V\^2 + E)