Remove commons-math dependency

[neoXfire]

commons-math is a 1Mo artefact. Only 4 classes of the library are used in this file.

I think it would be better to remove the dependency and shade or reimplement the statistics functions ? It would reduce the size of artefacts and images for containerized envrionments.

I can push some commits if you agree with me.

[AlexandreCassagne]

Regardless of your decision, Apache commons-math at version 2.2 suffers from a known vulnerability (described here).

Can a decision be made to either reimplement the function or bump the dependency to a later version (>3.x)?

[AlexandreCassagne]

See #26.