Hypotonic

* Support JSONPath extensions.
* Support array and callable params within get command.
* Support callable set values.

* Add `then` command for executing arbitrary functions.
* Retry failed requests with exponential backoff.
* Several error handling improvements.

* Support non-standard JSON content types.
* Add pagination via incrementing param.

* Add support for JSON responses.

* Build and release via Github actions.

* Allow passing lists into get and post functions.
* Expose running in an async mode.