Dev may2 (#167)

* Update ar_fit.m

Fixing bug in filename stepwise->stepwisefit, and the relevant extracted output.

* Update ar_glm_final.m

Reducing the number of max iterations to 10 for the sake of computational time.

* Update ar_glm_final.m

fix
Pmax 10->100

* AR p order

Order was hardcoded, changed it be 2 X sampling frequency.