Added /stack command to stack books using Bukkit's comparation system
rather than screwing around with comparing them ourselves like
worldguard.  This means that it won't stack books if they aren't exactly
identical(same name, same contents), it won't stack enchanted items,
etc.
Added a listener for when they try and put stacks into the brewing
stand.  Tried to test it locally and it wouldn't let me put stacks into
the brewing stand...  No idea.  
Rewrote the listener, it now works completely.