Added new types Additive, AdditiveUncorrelated and NonAdditive. Added fl::Real doc. Added AdditiveModelType, AdditiveUncorrelatedModelType, and NonAdditiveModelType for type deduction
Added new types Additive, AdditiveUncorrelated and NonAdditive. Added fl::Real doc. Added AdditiveModelType, AdditiveUncorrelatedModelType, and NonAdditiveModelType for type deduction

SimonEbner/fl,filtering-library/fl