Unify template-creation framework

[jcohenadad]

More and more groups are generating a specific spinal cord template, and I would like to make sure we centralize the developments into a single and centralized script, so that there is no parallel developments and the central script is always up-to-date (and can generalize to multiple applications).

@benjamindeleener: I am currently helping Shiva with the pediatric template. She has been using a script that you modified, from this repos, for her specific needs. Question is: is it possible to modify the script this repository to make it usable by Feroze's team?

@charleygros: You have also been working on the pipeline to generate a template for folks in Australia. Is there another script out there, or is this the one you used?

[charleygros]

@jcohenadad: I am using this script (ie there is not another script), using SCT v.3.2.4.