Add new mathx package

[cristinaleonr]

This PR adds math functions to a new mathx package.

I thought it was very unexpected that the math package does not have a "Min" comparison function for int.

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This change is 

[coveralls]

Pull Request Test Coverage Report for Build 1181

• 40 of 40 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 94.366%

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Totals
Change from base Build 1168:	0.1%
Covered Lines:	2127
Relevant Lines:	2254

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💛 - Coveralls