Fix examples/Sphere/generate_initial_conditions.py

[CFD-Xing]

The python script in examples/Sphere/generate_initial_conditions.py is broken.

First the from_stl function should only accept keyword argument. Providing the filename as a positional argument cause the following error:

epsi
Traceback (most recent call last):
  File "generate_initial_conditions.py", line 17, in <module>
    epsi[key] = epsi[key].geo.from_stl("sphere.stl",
TypeError: from_stl() takes 1 positional argument but 2 positional arguments (and 3 keyword-only arguments) were given

A lower case d should be use in gene_epsi_3D. The current script produce the following error:

Traceback (most recent call last):
  File "generate_initial_conditions.py", line 22, in <module>
    dataset = x3d.gene_epsi_3D(epsi, prm)
AttributeError: module 'xcompact3d_toolbox' has no attribute 'gene_epsi_3D'

This PR fix this issue.