IV mutagen insertion

These add IV mutagens to the Lab chem rooms; each is comparatively rare
but the amount of them should make the odds of one or two reasonable.  I
intentionally made Fish more common because there's no renewable way to
make it, IIRC: you need canned goods.

Also makes flavored mutagens recipe-locked (so, major Nerf) and includes
recipe books for all of them, which tend to spawn in relevant lab rooms.
But if you find one on a scicorpse, that's not a bug.  Check the item
ID.  :-)

Finally, adds lab notes to the computers to keep the backstory-support
going.