Star click

Fixes #783

This addresses the problems with the `star` art element clicks. The first issue was that the DSL `star` method wasn't properly set to take all the various options for parameters that it should, and hence didn't find the `click` procs we were passing to it.

Once that was fixed, there was also a problem with the boundary checking revealed, which I've addressed as well. Note that this doesn't fix the fact that `in_bounds?` is naive, and just a rect around the star. That'll get fixed with #778.

Also double-checked that `star` was the only affected art element. The others all click just fine.

:star: :star2: :stars: 
I'm not sure where we handle this everywhere else, might be worth unifying. My gut feeling would put it into `Star#initialize` as default arguments or in initialize, though.