1.5

new:

• add proper tests
• use black formatting
• add utils script to contain error classes and utility functions

updated:

• modify inspect so that it’s coherent across save and load
• modify playerday elo to a property attribute
• modify player log_likelihood computation to comply with tokoharu pull request
• modify player hessian, covariance and update_by_ndim_newton computation to comply with tokoharu pull request