function registerKernel(config) {
	  var kernelName = config.kernelName,
	      backendName = config.backendName;
	  var key = makeKey(kernelName, backendName);

	  if (kernelRegistry.has(key)) {
	    console.warn("The kernel '" + kernelName + "' for backend " + ("'" + backendName + "' is already registered"));
	  }

	  kernelRegistry.set(key, config);
	}
Registers the function (forward pass) for the kernel in a global registry.

@param config A config object with the following properties:
- `kernelName` The official name of the kernel.
- `backendName` The official name of the backend.
- `kernelFunc` The function to run during the forward pass of the kernel.
- `setupFunc` Optional. Gets called once, after the backend initializes.
- `disposeFunc` Optional. Gets called once, right before the backend is
disposed.