CubeFit: Regularized 3D fitting for spectro-imaging data

Cubefit is an OXY class that performs spectral fitting with spatial regularization in a spectro-imaging context. The 3D model is based on a 1D model and 2D parameter maps; the 2D maps are regularized using an L1L2 regularization by default. The estimator is a compound of a chi^2 based on the 1D model, a regularization term based of the 2D regularization of the various 2D parameter maps, and an optional decorrelation term based on the cross-correlation of specific pairs of parameter maps.