For new major release: Fix orthonormal basis for multivariate models

From CHANGELOG.md

[1.1.0] - To be released

• Fix computation of orthonormal basis for leaspy multivariate models:
  • <!> this modification is breaking old multivariate models for which orthogonality between space-shifts and time-derivatie of geodesic at initial time was not respected.
  • To prevent using old saved models (with betas and sources being related to the old wrong orthonormal basis) with new code we added the leaspy version in the model parameters when saved, you'll have to use leaspy 1.0.* to run old erroneous models and use leaspy >= 1.1 to run new models.
• Clean-up in code and in tests
• TODO/WIP: New methods for initialization (individual logistic regressions, LME) ?

Main commits to review

Main commits for fixing computation of orthonormal basis:

• 4c3b6236
• 22c24515 (simple just a few line for logistic parallel case)

Test refactorization (unlink tests using models from functional fit results) + update old wrong values...

• 5558f0c6