Enchanting table improvements.

The doxy-comment for this function is no longer valid - this function no longer implements 1.2.5's behavior, but is 1.7-specific instead. You should change the comment to document the current behavior, and fix the 1.2.5 protocol's enchantability-checking, so that it uses the old function's contents (the 1.2.5 protocol had extra data sent for items that could be enchanted, and there was an explicit list of such enchantable items).