Chrome OS support

[olofson]

Can we support Chrome OS properly? It would seem that it supports Android apps as well as (obviously) Chrome/web apps. Not sure about native apps. Technically, either way should work, as long as we can run "native" code (asm.js or WebAssembly might be close enough) and OpenGL(ES).

See also #402.

Potential issues (also applies to any platforms with "slow" CPUs or non-native code):

• Audiality 2 relies on integer/fixed point math, which is a huge issue for asm.js.
• The realtime rendered music and sound effects may still be an issue. Non-interactive music, and one-shot sound effects are trivial to prerender, but interactive music/sounds need to be refactored.
• Spinning planet, fire/smoke (Use a "fire effect" engine to render explosions #198) and the like may need low quality modes, or GPU implementations.