Work with merger of rules so Planet Cracker is registered as a blocking mega

[openly-retro]

Orbital crackers from the planet cracker civic don't block the construction of megastructures which remove the planets the crackers are built over, nor are they removed when the planet is

Main examples of megastructures that would do this are things like the matrioshka brain, hyperstructural assembly yard and the nicoll dyson beam from gigas