Support for textprotos

[pavel-klavik]

As far as I understand this library, it allows only to read protos from and into bytes. I would be useful to also add text proto support which is sometimes used for small config files.

It might look like this:

person {
  name: "John Doe"
  email: "[email protected]"
}

or this:

person <
  name: "John Doe"
  email: "[email protected]"
>