Many methods default to `pretty=True`, and use `print()`

I believe that nexus-forge is mainly to be used as a library (correct me if I'm wrong), and thus I find the decision to `print()` things pecurliar. Normally, I would expect a library to remain as quiet as possible, possibly using the `logging` or `warnings` packages to give feedback in error conditions.

In this case, however, the following API calls appear to print by default:
```
KnowledgeGraphForge.prefixes
KnowledgeGraphForge.types
KnowledgeGraphForge.template
KnowledgeGraphForge.resolvers
```

Could we reopen this design decision?