Make a fake reaction family for a 3-product reaction.

This was based on https://github.com/comocheng/RMG-models/issues/74
But it turns out that recipe was wrong.
Atom *5 ends up with too high a valance.
Committing it anyway, but will turn it into something else next.
Change the Fake_3products1 family into something useful.

This recipe at least works. I added a screenshot of some 
examples from the LLNL gasoline surrogate model.
Made another fake family with 3 products.

This one (Fake_3products2) is like the previous (Fake_3products1)
except there is already a radical, and you form a double bond.