Add ample testing from Abramowitz and Stegun to all Polynomials

[miguelraz]

In the test directory, include code function values of different polynomials as tests to verify answers are correct.
I have yet to find a more efficient method than copy pasting the pdf archives and manually checking each one.

• Legendre
• Tshebyshev
• Ultraspherical
• Tshebyshev of the second kind
• Gegenbauer
• Laguerre
• Hermite

[dlfivefifty]

You should use the more modern DLMF which replaces Abramowitz & Stegun: https://dlmf.nist.gov

[miguelraz]

@dlfivefifty thank you for chiming in and welcome!
I will update as I implement more coverage, but unless I've missed something, I don't believe I can find tables of values for the Orthogonal Polynomials in the DLMF that don't refer back to the A&S Tables -- though there are tables of zeros which we could consider adding in the future.

[dlfivefifty]

Ah, you are actually using tables. Then A&S it is