Created "THREE.Supports" object, which should centralize this stuff. So far it detects <canvas>, WebGL and WebWorkers; later it could detect for example GPU capabilities.

Not sure about name or location, but it's pretty tiring go through all examples when something changes, so it should be somewhere in the library.

Code duplication is bad: even html snippets with error message should be centralized somewhere, so that when new browsers arrive we wouldn't have to keep changing them in many places.