Proof of Concept: Call APIs from GB

Proof of concept for calling APIs from GB Studio. It's pretty messy but works well enough for simple use cases. Note: Use this concept sparingly, if you're not careful your game may include functionality that is visibly broken when played on real hardware or other emulators. Instructions 1. Download the latest dev build from GitHub links at https://github.com/chrismaltby/gb-studio (is currently re…