Computes 'Owen's T' function or the bivariate normal integral
using one of the following methods: the modified Euler's arctangent
series, tetrachoric series, or Vasicek's series. For the methodology,
see Komelj, J. (2023) , or the revised
postprint version with corrected contents and improved typography at
. Also see the alternative approach by
Vasicek, O. A. (1998) .