Undo setting PCE properties as protected
For the MetaModel class split some of the PCE-specific properties such as pce_deg, polycoeffs, clf_poly and more were set to be protected. Since some of these should be set by the user (e.g. pce_deg, pce_reg_method), these should be set public again.
Change this for the following properties:
- _pce_reg_method
- _pce_deg
- _pce_q_norm
Properties to discuss:
- _pce_reg_options
- _coeffs_dict
This affects the following classes
- PCE
- PostProcessing
- Engine (?)