Add multiscale entropy slope / fit computation (Costa 2005)

[DominiqueMakowski]

"Finally, to assist in clinical classification, we extracted two simple features of MSE curves, the slopes for small and large time scales, i.e., the slopes of the curves defined by SE values between scale factors 1 and 5, and scale factors 6 and 20, respectively. Results for the healthy and congestive heart failure groups corresponding to the sleeping period are presented in Fig. 8. There is a good separation between the two groups. Considering other features of the MSE curves, in addition to these slopes, may further improve the separation. Alternatively, methods derived from pattern recognition techniques, e.g., Fisher’s discriminant, may also be useful for clinical discrimination" Costa (2005)

Maybe extract the best polynomial fit and get its coefs?