Improve numerical util files and testing infastructure

[msluszniak]

Description

Adds improved numerical module, and better testing infrastructure with tests.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update (improves or adds clarity to existing documentation)

Tested on

• iOS
• Android

Testing instructions

• Run examples using normalization, softmax, and meanPooling
• Run tests as describe in README.md inside tests directory

Screenshots

Related issues

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly
• My changes generate no new warnings

Additional notes

[msluszniak]

I overzealously changed norm normalization to z-score normalization. I will fix that.

EDIT: Updated and ready for a review.