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: 

No, I don't. IMO, returning some false value is the right thing to do here.

>  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. 

If we were using other Perl constructs, you'd `die` here, and give an opportunity to the calling code to recover.  In most cases the exception would abort the component, but there would still be a chance to handle that.

If you call `$self->error` you are forbidding any recovery action.

> 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

Neither am I. It's just that I don't want that road blocked.