Bugfixes and refactoring

 - Moved uristqwerty.gui to uristqwerty.gui_craftguide (freeing the package name for possible future work)
 - Combined and split CommonUtilities.getPrivateValue(): Combined the three versions into one varargs, split out a getPrivateField
 - Added CommonUtilities.getItemDamage(): Unlike ItemStack.getItemDamage, doesn't NPE if the stack's Item is null, instead using reflection as a fallback to read the field directly
 - Oredict entries with 0 items show the associated oredict name
 - Added CommonUtilities.checkItemStackMatch which checks whether two stacks match, considering the wildcard damage value. Replaced three separate places that implemented the same logic with a call to the method