Workspace and model getters return references since they cannot be null
Prior builder can now generate a cruvature function
Modified to correctly use the MatrixModel reference getter
Prior builder curvature now generates a regularization PDF
Pirors can be set into the model
Added custom PDF. Minor change to curvature
Checking that the curvature PDF is in the workspace
Fixes and cleaning of priors
Squred curvature instead of absolute value to help with PDF normalization
Fixed variable for xsection variable error
Priors now configurable