Just a quick note for those of you worried about loading existing single player worlds after the last update:
Don't worry about the message regarding missing mods/blocks/items when you load existing single player worlds, it's perfectly fine to go ahead and load them as normal.
If you did have any of the blocks from those mods placed, which seems unlikely as they were useless in single player, they will be removed from the world/s without any issues. We tested this several times, and in a few different ways, without a single issue.
Enjoy!