Can handle any heigth and width of occupancy grid? YES
Possible to specify multiple goal nodes? YES.
Fast and efficient? YES.
Possible to specify connecting distance to other nodes? YES (in other words the algorithm is not restriced to 8-directions)
There are no nested functions, subfunctions, plotters, or any other mess in the actual pathfinder script.
Algorithm has simple inputs: An occupancy grid. A goal Matrix, the start node and preffered connecting distance.
The zip file includes an example on the use of the script.

See linked GitHub page fore more information.
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This code was written for a project, which I have written a paper about:

http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2655682

This paper provides some more details on the code, and how it can be applied in a practical example. If you use the code for academic work/publishing I will appreciate if you could cite the above paper.

There will probably soon come an update, which among other, will include 3D pathfinding. If you liked the code, please give it a positive rating.