feat: New thresholds, fat segmentation, and plots

Muscle threshold was added as input for degenerationAll.m and
muscleDegeneration.m functions to allow easier testing of different
values. The way thresholds are used was changed: the muscle or
osteochondroma threshold introduced as input is the threshold from which
this pixel can be considered muscle or osteochondroma. Consequently, the
value used in imbinarize for image thresholding is
(HUThresholdMuscle - 1) or (HUOsteochondroma - 1) (see MATLAB doc for
imbinarize). Segmentation of fat infiltration was updated so that it's
now the fat directly that is segmented and not the atrophied muscle
without fat. Plots were also enhanced with the addition of case ID in
the title and addition of a legend.