Normalise node type names

[knoxsp]

Remove non-alpha characters from node type names coming from the template, and make them lower caase, allowing for the template to display more user-friendly names, while maintaining compatibility in pywr

[pmslavin]

It is quite common in existing models to use numbers in node names, especially at the end to distinguish nodes within some kind of group, e.g. "Generator 1", "Generator 2", "Abstraction T1", etc. The re.sub would collapse all such names down to just the same alphabetic characters.

Is there a case for enforcing "variable name" convention instead, where digits can be present in a node name anywhere except as the initial character and underscores used to allow "spacing" between parts of a name?

[knoxsp]

I think the proper solution for this is a hydra solution where template type names have a 'code' and a 'label' where the code must not have spaces, and can only contain a specific set of characters such as alphanumeric characters and - and _, and maybe a select few others... -- something like: [a-zA-Z0-9-_]

This would require a new column (code?) on template type, populated by default with the normalised name of the 'name' column in the upgrade script.