renaming undocumented Bessel functions g0, g1, gn



Hello,

I wonder if it's OK if I rename the functions g0, g1, and gn (in
src/bessel.lisp)
to bessel_g0, bessel_g1, and bessel_gn, respectively.

These functions are g0(x) = exp(-x)*I[0](x), g1(x) = exp(-x)*I[1](x), and
gn(x,n) = exp(-x)*I[n](x). I can't find any documentation for them
(neither under their own headings or under something else).

A letter followed by an integer is a popular scheme for naming
variables and functions so it's pretty easy for a name invented
by a user to collide with one of these (which is how I found them).

Robert Dodier