[Feature] Generalise template building further

[alessandrofelder]

Is your feature request related to a problem? Please describe.
We'd like to minimise work needed to create a new template from new source data.

Describe the solution you'd like
A well-designed and documented way to make a template that

• uses default methods for each step, to minimise effort
• avoid duplications by e.g. ensuring default names for files, and writing intermediate files, and the default methods for template generation steps mentioned above.
• makes it easy to customise steps for which the new data is tricky

Describe alternatives you've considered

\

Additional context
Currently considering decorator, strategy and template pattern, but also might like to think about non-OO approaches to this, that might be simpler.

[alessandrofelder]

Some pseudocode for idea:

from template_building import TemplatePrepper

# for easy atlases
if __name__ == "__main__":
    crab_template = TemplatePrepper("crab")
    crab_template.run()

#----------------------------------------------------


# for harder atlas
class DifficultTemplatePrepper(TemplatePrepper):
    def __init__(config):
        pass

    def initialRegistrationStep(self):
        # do a fancier initial registration
        pass


# for hard atlases
if __name__ == "__main__":
    crab_template = DifficultTemplatePrepper("crab")
    crab_template.run()