Use polynomial equation

[adriengoeller]

To use the polynomial equation resolution provided by #76, we need to use it to:

• get the deformation for a given sigma with polynomial only
• get the linear parameters after plastification and store it with the sigma_max (for each span i.e. this is a vector)
• get deformation for a given sigma when sigma < sigma_max
• mechanism if sigma in input > sigma max: get the new parameters after plastification and store it