Interpolate references in class names

[Petr Michalec]

• kind of class parameter mapping
• in order to avoid templating if/else in class spec. (which is not available, and when used with cookiecutter it breaks lifecycle of the repo)

Existing implementation under #26 (#26 (comment)) is just partially functional and thus was reverted at #29 and be refactored. Please comment here what you would like to have it working.

Example:

classes:
- first
- network.${_context:network:load_balancer:engine}

The idea now, unless code will allow better behaviour, is to rather load these context class params from external yaml, pointed from CLI or Config, and push to each class Entity when created by default instead of empty Entity.parameters dict.

[Petr Michalec]

resolved by #37