Robert Garrett
8f6dfc3e49
Added a `FuelChanged` event which is to be used to trigger Observers watching for a machine's fuel level change. I've written a slapdash observer to emit these events when the cutting machine's big red button is pressed. That observer *must* be replaced because of how it feeds the machine ID into the UI (it only works when there is exactly 1 CuttingMachine, which won't be the case). The dummy machines are missing their machine components. I've added the `CuttingMachine` component to the cutting machine just to test the event passing.