Program 12.2 update and spherical Bessel functions

[Jay Wang]

SciPy changed the name and behavior of the spherical Bessel functions in ver. 1.x.x. Program_12.2_qmscatt.py (and .ipynb) are updated so it will detect the SciPy version and use the correct signature. Three changes occurred in SciPy ver. 1.x.x:

1. name change: spherical_jn/yn(n, x,flag) from sph_jn/yn
2. behavior: if n is an integer, a single value if returned; if it's an index array, an array of values is returned; previously an array of values for indices up to n is returned.
3. returned values: if flag=False (default), function values are returned; if flag=True, derivatives are returned; previously both function values and derivatives are returned in a tuple.