Add virtual recipes for oredict entries.  Resolves #3.

This addresses #3 in an IMO reasonable fashion.  If an oredict entry is an ingredient to a recipe, users can use the recipe switcher gear to switch between all the recipes that can craft any of the items that satisfy the entry.  Or they could, if that gear worked (it doesn't do anything for me, some clientside exception).

This change is pretty rough around the edges (I don't think it handles fluids correctly / at all...) so don't merge it in without very careful inspection.  Please do however take a look at its behavior and let me know what you think.

Ironically, it doesn't seem to handle wool correctly, but other items such as ingots, sticks and logs do work properly.  I'd suggest looking at the fence gate for an example of its behavior.