Update demo scripts to reflect newer additions to the API

[tferr]

Once SNT 4.3/5.0 is released, it would be great to modernize some of the demo scripts to reflect the newer additions to the API. A good candidate is Sholl_Extract_Profile_From_Image_Demo.py discussed here.

(cc'ing @saramcardle)

[imagesc-bot]

This issue has been mentioned on Image.sc Forum. There might be relevant details there:

https://forum.image.sc/t/snt-critical-value-and-branching-index-via-script/94018/4