Hungarian Algorithm for Linear Sum Assignment Problem

Hungarian algorithm for linear sum assignment. Works for square as well as rectangular cost matrices
(thus, for the common example of matching M workers to N tasks, M can be different from N.)
The speed is compared to two other existing matlab implementations.
This implementation seems to have an edge for rectangular cost matrices; for the tested problems it runs more than 10x faster (see graphs on github: https://github.com/ondrejdee/hungarian)