83bb7fd makes ice melt when exposed to light. I have a world with a lot of ice directly next to light sources, so this change can definitely screw up existing worlds. Maybe provide a config option for this?

For now I've just commented out these lines of code in my local copy of the mod.

Some pre-destruction screenshots just to guilt you into adding this option for MC 1.12 (Don't worry, I made backups, my world is fine)

I want to maintain consistency with vanilla, so I'll make you a compromise. I'll make sure Chisel is compatible with mods like Icy U Melting which disable the random ticking of ice.