Release v2.0.2

This is a minor release with incremental improvements made during the review of the script in the Journal of Open Source Software. The following features were added:

• Some tweaks in the plots to make them look better and avoid blank spaces when using Jupyter notebooks
• Improvements in the documentation of some functions.
• Use np.sum() instead of sum() throughout the script for consistency
• The calc_diffstress function indicates the valid names when the piezometer is misspelt