Initial Chicken Scheme Support

If you are able, could you please give it a smoke test before merging?

I've given it a look over myself; but I must admit I'm quite weary from the late, short nights with my newborn, and I am not totally familiar with Geiser's full functionality.
there's an error in this re: `|`  should be `\\|`.  also, are module names necessarily a list? if i try in the repl to enter a module named `(foo)` using `,m (foo)` i get an error, but defining a module named simply `foo` and doing `,m foo` seems to work...