Questionable feature idea: limit size of `featuredPortlets` to some reasonable limit.  

Aside: 
> Doctor, doctor, it hurts when I do this!
> Then don't do that.

I suspect that limiting is manageable enough by "Don't do that" in regards to, implementors, keep your Featured group size under control, but the portlet is going to look pretty silly if there are 80 Featured portlets, so maybe since it's designed for 2 +- 4, it should go ahead and save adopters from themselves and cap display at six-ish?

I'm torn.  If we don't put the fail-safe in the code, I suspect we're going to trip over this.