My players have been working very hard on a city in my "creative" world. The map was started as a 1.7 world, and has persisted all the way through 1.0 without trouble. Unfortunately, when I upgraded to 1.1, a snow biome was dropped right on top of our city, completely blanketing the city in snow. Is there any way that I can fix this? Do older terrain generators exist - maybe I could replace the default with a custom one with no snow?