Potion Improvements

I think the creation of potions in MCreator is a bit tedious to do without custom code if you want to do it right. Here are my suggestions:

1. Make the creation of custom potions more like the creation of items, where you can choose custom textures and put the potions in specific creative tabs.
   OR
2. Merge the creation of potion items into regular items, the same way music discs are made. (this would allow everything to be more straightforward.)