Astray runtime packaged for PLAYCHIVE

Upstream repository: https://github.com/wwwtyro/Astray
Pinned revision: d3c4f61f2cbbe35752fbfa205f85a41d7f9fe0f0
Upstream demo: https://wwwtyro.github.io/Astray/

The upstream repository releases Astray under the Unlicense/public-domain
 dedication (ASTRAY-UNLICENSE.md). The source snapshot retains its bundled
Three.js, Box2dWeb, KeyboardJS and jQuery files exactly as supplied upstream.
This package makes only static-hosting path corrections: the three texture URLs
were changed from origin-root paths to local relative paths. No playable asset,
analytics script, user upload, account, server or remote game-data request is
used by PLAYCHIVE.