Any encoders with the same indent share a cache. Only one assignment is made on depth change.

`space` is equivalent to the third argument of [javascript's JSON.stringify](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify)

Turns out using the environment has zero performance benefit in any version of lua, so it just serves to make the code less readable

This brings the interface more in line with the rest of the library

This doesn't really do anything for consumers, however it is valuable for ensuring variables are made local