A* Algorithm and other small updates and fixes.

[OpenSauce]

Hello!

Closes #2

In this I've added an A* method with the relevant heuristics. I've also included the update of the original function to use a map for faster lookup. If there's anything you want changing or adding let me know.

[OpenSauce]

Closing as repo is not maintained

[SolarLune]

Closing as repo is not maintained

I just merged a PR a few weeks ago, so the repo isn't unmaintained; I just forgot to review this PR, sorry.

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As for the PR itself, I believe it could be useful to have A* pathfinding, but I think it would be better to simply rewrite the existing pathfinding function to accept a customizeable path searching algorithm, rather than having a separate function for A* pathfinding (or even just make A* the default).

There were also a few spelling issues ("Diaganal" instead of "Diagonal", "Manhatten" instead of "Manhattan").

It also would be good not to use individual letters for values unless it's very obvious what they do (i.e. Node.g and Node.h should probably be something else more descriptive).

In short, A* pathfinding could be very good, but it would need to be approached cleanly (ideally, in a way that makes the existing pathfinding system even cleaner).