Feature request: Implement A* JPS (Jump Point Search)

I'm never sure how much preamble to put into feature requests, but first of all would like to say thank you so much for creating such a useful library and set of tutorials. I've found both absolutely invaluable in learning to programme games and improving my Rust skills in general, it would have been a much harder slog without.

Onto the feature request: I'm using the A* algorithm for real-time path finding and overall it works really well, however in a similar situation to issue #134, where a the direct route to a target is blocked, but a circuitous route does exist the performance can drop dramatically trying to figure out alternative routes. [JPS](https://harablog.wordpress.com/2011/09/07/jump-point-search/) looks like a substantial optimisation on A* that can help in situations such as these as well as providing a general performance boost.

As it is an algorithm specifically designed to optimise path-finding over homogeneous grids it would likely be a great benefit to the development of games in general and in particular rougelikes.

My Rust skills and general knowledge of path-finding are definitely in their infancy, but I would certainly be happy to try and take a crack at this at a later date if others might find it useful / nobody more knowledgeable than myself beats me to it.