support ncm-metaconfig based on TextRender 

Additional fixes and unittests to allow ncm-metaconfig based on CAF::TextRender 
i can make it dynamic (what to do on error: `verbose`, `info`, `warn` or `error`) and save the error message in e.g. `$self->{error}`; but i'm not sure you'll like that :smile: 
however, i'd consider this the exception. imho most usage of `CAF::TextRender` will imply that such fatal error is also a fatal error for the component, and thus every component will have to redo the same error handling. 
also, i'm not sure how to recover from these fatal errors. e.g. for this error, there's a clear mistake in the module when calling `CAF::TextRender->new`. the only way to recover from that is by fixing the component. another example, how would you recover from a missing or buggy template?

with the dynamic implementation, advanced recovery logic can be added to the component if one chooses; but i don't see much added value.