Design: templates should allow onyo pseudo keys and <labels>

[aqw]

This came out of a conversation that Ben and I had, that built on some ideas that Tobias and I had been talking about awhile ago:

Templates and Assets are basically the same thing. It's just that some validation rules do not apply for templates:

• pseudo keys are allowed
• <labels> are allowed (or do we call them tags)?
• keys and values in the asset-name do not need to be set
• other asset-level validation are not applied

All assets can be used as template, but not all templates are an asset.

Another way of looking at this:

• everything that can be passed to --keys can be used in a template (and thus also --yaml, etc)

See also:

• Design: allow onyo new to accept values in YAML files #703
• Design: onyo set --yaml #720