To make it easier to maintain and release versions of the enhancer we should move all enhancement engines in /enhancer/engines into /enhancement-engines.
By moving the engines into their own top-level folder we can release them separately. We can also release some of them along with an enhancer release if we like.
Note: The former approach was to move only some of the engines. But we came to the conclusion that it makes no sense. Instead move all of them.