This function computes Gauss-Chebyshev base points and weight factors
using the algorithm given by somebody in 'SomeBook',
page 365, Academic Press, 1975, but modified by a change
in index variables: j=i+1 and m=n+1.
The weights are all wf_j=pi/m
and the base points are bp_j=cos((2j-1)*pi/2/m).