Text type?

I wonder what you think of adding a dedicated text type, which would be identical to the bulk-string, but would indicate UTF8-encoded unicode text as opposed to an arbitrary blob of bytes?

The difference to the client would be equivalent to how Python 3 differentiates `str` (for unicode) and `bytes` (for blobs). I think msgpack has [something similar](https://github.com/msgpack/msgpack/blob/master/spec.md#str-format-family).

Or perhaps this is the intended use-case for the "verbatim string" type?