Dont show variables

[benbc]

This is more speculative than my other PR -- since I'm discarding information I could imagine you might not like it. I'd be happy to add a command line flag to trigger this behaviour if you prefer, but my feeling is that it's so likely to be the right thing to do that there's no need to bother the user with it.

As you can probably tell, I found myself making heavy use of "variables" in my modelling.