Results 5 issues of Kai Marshland

Fixes issue #4. Additionally, adds a basic test.

Currently, there's nothing in the documentation (at least that I can find) about saving jpegs as progressive, despite it being supported. This should be updated. For reference, the following default...

This library should call [unmountComponentAtNode](https://reactjs.org/docs/react-dom.html#unmountcomponentatnode) in order to fix a memory leak. The react team states "This is important and often forgotten. Forgetting to call unmountComponentAtNode will cause your app...

In production (running on render), I'm seeing occasional latency spikes. End-to-end, it typically takes a few tens of milliseconds for a message to go through, but occasionally this spikes to...

investigation required

Is there a way to release the GVL/GIL? I saw in https://github.com/matsadler/magnus/issues/12 that it wasn't in Magnus yet, but that was 2.5 years ago. For reference, my use case is...