Error message quality: `parse` vs `iparse`

[marcosh]

The usage of parse or iparse produce different error messages, since the former is excluding the information about the JSONPath of where the parse error happened.

This means that different functions (e.g. fromJSON and decodeEither) will produce error messages with different error quality.

I think it would be interesting to at least document which functions produce error messages which provide information on the error path and which ones do not