* Focus the previous recipe if it's still visible when loading usage recipes.
* Reduced code duplication by extracting getRecipeHandlers
* Moved RecipeHandlerQuery to its own package-private file
* Refactored RecipeHandlerQuery methods
* Saving the current recipe when left clicking a machine's "Recipes" button
* Restored prevScreen so we can restore it with overlay
* Genericized GuiRecipe so that currentHandlers is no longer hidden in subclasses
* Cleaned up overlay handling
* Fixed trivial IDE warnings & bad JavaDoc on files I touched
