Integrate Oozaru into Sphere GDK toolchain

[fatcerberus]

Currently Oozaru, the Sphere v2 engine for the Web, is its own thing, with its own GitHub repository:
https://github.com/fatcerberus/oozaru

The plan is to bring Oozaru into the fold as a first-class part of the Sphere toolchain, so that games can be readily tested with it, and so that cell build always produces Oozaru-compatible output. There should also be an option to produce a Web-ready dist that includes the engine and can be directly uploaded to a web server.

Oozaru will be versioned in sync with the rest of the Sphere platform (5.5.2 at the time of writing); this means that at the very least, it must be a full Sphere v2 API implementation. It's currently missing some lesser-used features, so that must be rectified first.

[fatcerberus]

Note on the "full implementation of Sphere v2" point: API 4 will be the baseline target in order for a game to run in Oozaru. Some functions in API 3 and under are not practical to support on the Web, so Oozaru is unable to support these and they will be disabled in API 4+ to pave the way for seamless cross-compatibility.