invalid json and bindata repr

[devsnek]

I've discovered a couple of issues while working with the json api.

• Sometimes bindata is an array of numbers instead of a string. This makes consuming the data a painstaking task. Luckily, string sequences in json can contain unicode escapes, so this can actually be safely represented as a string instead of an array of numbers.

• Sometimes there are invalid escape sequences in bindata strings (for example \199). No conformant json parser will accept it. Luckily, the same unicode escape sequences mentioned in the above point can be used here.

I would normally try to contribute something like this myself, but the portability requirements of this code are well beyond my expertise 😅