[ogcqfppx] Easy access to paraboloids

When making any bowl-shaped object, e.g., tableware, choose a paraboloid (likely truncated by a plane) as the shape unless there is a good reason otherwise.

Easy access shapes able to concentrate or emit parallel rays might be useful for education and tinkering.

Maybe there's a danger of shiny objects catching the sun a just the right angle and setting things on fire.  A nanny state might ban paraboloids for this reason, though the conspiracy theorists would theorize that the government doesn't want to make it easy for the populace to build radio dishes.