Add printing and dumping item information and NBT data.

When right clicking on air with a gold nugget, the info for the item
to the right on the hotbar will be printed/dumped.
Change item info debug tool into a Blaze Rod. Some output format clean-up.

Having a different debug "tool" for items gets rid of the annoying
fact of getting both block and item debug info at once.
Only allow OPs to use the "debug items".