implement 'schema translate' without copying data

[thomasdfischer]

Problem

There is an edge case in schema translate where, if any part of the input data is parsed as a map[interface{}]interface{}, then data must be copied. This is because all of the JSON/YAML/TOML/etc. packages do not support encoding map[interface{}]interface{} objects. To allow translate to still work, the map[interface{}]interface{} object is converted to a map[string]interface{} object by

1. Making a new map[string]interface{}
2. Looping through the original map, inserting all the values into the new map (which has string keys instead of interface{} keys)

The conversion is so costly that translating an 8MB file takes 8 seconds on my ThinkPad T450s. This is not acceptable.

Possible Solutions

1. Write custom decoders and encoders which automatically attempt to convert interface{} keys to strings.

2. Find someone who knows more about Go's type system to refactor the current code so that data is cast to the correct type without copying it.