Bessel functions

[jorenham]

• cyl_bessel_j
• cyl_bessel_je
• cyl_bessel_j0
• cyl_bessel_j1
• cyl_bessel_y
• cyl_bessel_ye
• cyl_bessel_y0
• cyl_bessel_y1
• cyl_bessel_i
• cyl_bessel_ie
• cyl_bessel_i0
• cyl_bessel_i0e
• cyl_bessel_i1
• cyl_bessel_i1e
• cyl_bessel_k
• cyl_bessel_ke
• cyl_bessel_k0
• cyl_bessel_k0e
• cyl_bessel_k1
• cyl_bessel_k1e
• besselpoly

[Copilot]

Pull Request Overview

Adds comprehensive support for Bessel functions including cylindrical Bessel functions of the first and second kinds, modified Bessel functions, their exponentially scaled variants, and the Besselpoly function.

• Implements 21 Bessel function variants covering all major types (J, Y, I, K) with order 0/1 specializations and exponentially scaled versions
• Adds function bindings with proper type signatures and descriptive documentation strings
• Improves consistency in existing documentation by standardizing terminology

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/lib.rs	Adds Bessel function implementations using xsf_impl macro and standardizes existing documentation strings
build.rs	Adds type signatures for all new Bessel functions and improves comment formatting consistency

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