Kernel utility module.

Add a `kernel/utility.js` module to eventually hold internal kernel utilities and utilities that drivers may need when interacting with the kernel. This is a predecessor to `branch/node-references`, which adds functions for mapping between nodeIDs and kernel node references.

@eric79, please review.

That would be appropriate if it were just the kernel. But other modules already commonly use `utility` to refer to `vwf/utility`.

The kernel will need a name for `vwf/utility` too when it becomes a [RequireJS module] (https://github.com/virtual-world-framework/vwf/blob/branch/model-sandbox/support/client/lib/vwf.js#L43), and I think it's best to keep the same name that the others use.