No cursed biomes

This mod removes the "cursed biomes" mechanic. I hadn’t seen that there is already a mod for this, but I’m still uploading this one because it works in a different way: - the mod linked above works by modifying data related to boss cells difficulty, so it is incompatible with other mods that modify difficulty settings (eg. legendary forge caps, healing fountains); - this mod works by turning on the "CannotBeCursed" flag on each level, so it is incompatible with other mods that modify level settings (eg. mobs in a level, number of scrolls in a level).